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Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

CORUNDUM (RUBY, SAPPHIRE)


CORUNDUM (Korund—Corindom— орунд) (Pliny the Elder, 77). Kurundam – from Tamil; Kuruvinda – Sanskrit; karand – Hindu. Ruby – from Lat. rubeus, red (Valerius, 1747). Sapphire – from Gk. sappheiros, blue; the antique name of lazurite. The term sapphire is accepted only in the 12th cent. Padparadschah – color of lotus in Singalezian.

Composition & Properties. Oxide – Al2O3, trigonal system. Color → admixtures: red ruby – chromium (Cr3+), blue sapphire – iron (Fe2+/Fe3+) = 1; bluish-green sapphire – vanadium (V3+), green sapphire – iron (Fe2+ /Fe3+) = 0.5; yellow sapphire – iron/oxygen (Fe3+/*O); pink-orange padparadschah – chromium/oxygen (Cr3+/*O ); colorless leucosapphire – without admixtures. Notice – *electronic centers of coloration. Hardness 9. Density ~ 4. Luster vitreous to adamantine. No cleavage, well-manifested parting, sometimes following two directions. Fragile.

Noble corundum has been known and valued as a gemstone since ancient times. Transparent varieties of corundum are of particular interest: ruby, sapphire, and padparadschah. Noble ruby or oriental ruby may be colored bright red to violet-red, padparadschah – rose-orange. All other color modifications of noble corundum qualify as noble sapphire – rose sapphire, green sapphire, yellow sapphire, leucosapphire and violet or purple sapphire. The most subtle tints are considered in names of precious corundum: light rose – rose ruby, light red – sangena ruby, light brown – vermeil ruby, brownish-rose – hyacinth sapphire, yellow-brown, spotty – golden sapphire, green-yellow – gold sapphire, dark blue – indigosapphir and black sapphire. The line of demarcation between ruby and rose and red-violet sapphire is suggested to determine from standards or colorimetric tables. Corundum is found as short-columnar, tabular, barrel shaped crystals, here and there sharpened at both ends. Opaque crystals of corundum sometimes are to 1 m long and their weight may be as great as 152 kg. The parting with diamond luster typical for it is well defined in diamond sparadamantine or demantspath. A distribution of color can be even, zonal, spotted or more complex. Its intensity for ruby depends on chromium content, while admixtures are responsible for tints. High iron content will give rise to red-brown color, and the presence of vanadium induces violet hue. Degree of iron oxidation, or availability of titanium admixture will effect different tints in sapphire: the predominance of iron (Fe2+) results in yellow color, blue and green colors are governed by variations in quantities of iron (Fe2+ and Fe3+) blue tint being connected with considerable prevalence of iron (Fe2+).

In the presence of finest parallel-fibrous channels or mineral inclusions in rubies or sapphires mild silky luster appears that is called effect of silky. Its most pronounced demonstration is effect of cat’s-eye that can be seen on a cabochon surface as a distinct luminous stripe moving when it is turned relative to a light source. Every so often the term sapphire cat’s-eye is erroneously used for slightly cloudy opalescent sapphire – girasol sapphire with a floating light speckle or an in distinct broad luminous stripe. Yellowish or reddish sapphires of such a type are also called oriental sunstone. Asterism may be thought of as a manifestation of silky effect too. In the case of star ruby and star sapphire it is related with inclusions of needle-shaped rutile and other minerals arranged parallel to edges of a crystal apex. This optical effect in a properly oriented cabochon is observed in reflected light as an iridescent figure of radiant star of six or 12 rays. If this effect is seen in translucent light it is called diasterism. Asterism of rubies and sapphires in Myanmar is associated with inclusions of carbonates; at deposits of Taiwan it is accountable to titanomagnetite or hematite and in Congo (form. Zaire) – to inclusions of mica. By analogy with trapiche emerald where inclusions are located along edges of an apex, corundum of such a type, with a 6-radiated star, are sometimes called trapiche corundum. The availability of flaky inclusions of hematite in corundum causes iridescence and the effect similar to aventurescence. Alexandrite effect of coloration induced by admixtures of chromium (Cr3+), vanadium (V3+) and iron (Fe3+) is met in alexandrite sapphire. It is manifested as a change in color depending on a character of a light source. Sapphire is blue or green in bright daylight, in electric light it is red-violet. Color varieties of corundum are characterized by pleochroism. Especially heavily they are stained along the main axis coinciding with an elongation of a crystal. Cut a stone one should take an account of this feature. Pleochroism from dark red to orange-red is exhibited by ruby, blue sapphire shows a range from violet-blue to blue-green, padparadschah – from yellow-brown or orange to the true white. The play of color observed in cut pale sapphires may at times show itself as bright flashes of light that are called effect of fire. Besides, the presence of iridescence was noted in sapphires of Australia. It is connected with a natural jointing of the minerals.

Deposits. Corundum is generated in migmatites, pegmatites and metamorphic rocks. It is also met at contact-metasomatic deposits – in the rocks poor with silica. Due to the high hardness, the mineral was accumulated in placers where it has been extracted from since antiquity. South-east Asia was the only source of noble corundum in the antiquity. More recently, India, Africa together with Madagascar, Australia and Brazil became the regions of its extraction. There are no deposits of noble corundum with commercial reserves in Russia. Crystals of crimson opaque corundum of size 15x10 cm. were found in amphibolites in the Dyadina Mt., near the Chupa railway station, the North of Karelia. In high aluminiferous gneisses of the same area the Khitostrov deposit of rose opaque corundum with length of crystals up to 10 cm. developed to provide a collection material. At the Kola Penin. severely flawy blue sapphires the size of up to 1.5x2 cm. were traced in xenoliths of hornfels of the Khibiny alkali massif on the Vuonnemiyok creek, Eveslogchorr Mt. Occurrences of crystals of opaque corundum are known over vast expanses extending from the Polar Urals – the Ray-Iz massif – to the South Urals. In the Polar Urals, in 1975-1978 worked was the ruby Makar-Ruz’ deposit of the dunite massif Ray-Iz in a lens-shaped body of plagioclasites, with the size 5x20 m. The size of ruby crystals ranged up to 10 cm. across, somewhere they showed asterism. The output of the rough materials for cut was extremely insignificant. Because of numerous flaws, these crystals are classified as diamond spar and are satisfactory only as the collection stuff. In the South Urals Kyshtym first discovered the occurrence of blue sapphire in the Borzovka placers in 1823. At that time, it was called borzovite or kyshtymite and once the given mineral had been identificated by Ju. V. Soymonov its name was changed to soimonit. In 1858, transparent blue sapphires were detected in the Kornilov Log. The stone that after cut was presented to Alexander II had been found just there. Later on, in 1904, rubies up to 2.5 ct. occurred by the village of Koltashy near Yekaterinburg. They were encountered in gold-bearing placers, which have been worked out by now. Corundum in the form of barrel shaped and tabular crystals is found in alkali pegmatites of the Ilmeny Mts. Their size may be as much as 20x10 cm., but all of them are non-transparent and may be of interest only as the material for collections, especially when we deal with growths in the shape of “roses” up to 20 cm. across. Occurrences of noble corundum in the South Urals were also known previously at the Karamankul mines in the area of the Plast town. A number of sapphire finds, mainly in pegmatites, was revealed in the 1980-s in East Siberia. In the Eastern Sayan Mts. they were discovered in the upper reaches of the Tana-Oi River. In the Lake Baikal area they are seen at the Tazheranskiy deposit in the massif of the same name. On Lake Baikal, Ol’khon Is., star sapphire up to 15 cm. across was found. Star sapphire and a fragment of corundum of weight about 2 kg. were encountered at the Khapsug deposit in the Sangilen Ridge, Tyva (Tuva) Rep. Opaque crystals of sapphire 2 cm. in length were withdrawn incidentally from the gold-bearing Kartun placer in the Kedrovka River basin in the Krasnoarmeyskiy area, Primorskiy Region. Here too, sapphires are present in the crust of weathering of alkali basalts at the Pervomaiskii locality in the Small Khingan Ridge. The Nezametnoye deposit is known for jewelry sapphire and hyacinth extracted from a placer was discovered in the valley of the river Kedrovka in the middle reaches of the rivers Great Ussurka and Bikin. Sapphire here represents blue, green and blue-green crystals up to 3 cm. in size. Sometimes they exhibit silky effect and asterism. In Tadzhikistan, in 1979, in the East Pamirs Mts., the Turakuloma ruby deposit was revealed in the Muzkol Ridge, the Murghob Dist. Rocks enclosing rubies represent marbles changed to skarn. Dimensions of ruby crystals are from 3 to 10 cm. The sizes of the largest crystal of weight 1,465 kg. reached from 9 to 17 cm. There with, the crystals are predominantly transparent, and a minor part of them is translucent. In their color these rubies possess typical “pigeon-blood” coloration. In Kyrgyzstan there are interesting placers of sapphires on the northern slope of the Turkestan Ridge in the headwater of the Oramazansu River. The Tyuya-Muyun deposit, near Osh, where finds of ruby take place is situated in the same region.

As for Europe, in Scotland it is appropriate to note a small deposit of noble corundum on the islands of Lewis and Loch Roge. Sapphires up to 5 cm. long, suitable for cut were found there. Outcrops of rocks with crystals of non-transparent corundum up to several centimeters across occur in Finland, to the North of Kittilä. Being polished, some of them show asterism, therefore they were called Laplandia star. In Spain, near Málaga, ruby mines were opened in the 7th cent. In F.Y.R.O. Macedonia rose semi-transparent corundum was found in dolomite marbles near Prilep. In spite of their length, that can attain 15 cm. and considerable weight – up to 1.4 kg., the crystals are good only for producing of cabochons and balls. Aruby crystal of weight 7,000 ct. had been found there, too.

In Africa the leader by the number of deposits with noble’s corundum is Tanzania (14). The most interesting of them is located near Manyara Lake in the vicinity Majhi-Moto settlement where alexandrite, emerald, and other gemstones are developed together with ruby. A sizable deposit of ruby and motley pale Tanzania sapphire is seen in the valley of the Umba River, not far from the border with Kenya. Excellent orange sapphires were extracted in the same area. In 1980, another deposit of transparent ruby was discovered in the Morogoro Prov., near Makhenge settlement located in 100 km. to the south of Matombo. In 1994, in the south of Tanzania sapphires with alexandrite effect were found in the area of Tunduru and Sonega of the Ruvuma Prov., near the Mozambique border. They are blue-brown or gray-violet in daylight and grayish, green-blue in artificial light. Moreover, in the north of the country, in the Matabu Mts. and in proximity to Longido, green amphibole-zoisite rock – so called ruby matrix containing crystals of rubies up to 4 cm. across were discovered. Because of their opacity, these rubies are satisfactory only for making of cabochons. As to its color, this ornamental rock has received the commercial name anyolite in accordance with the word “anyoli” that means “green” in Masai. In Kenya a significant deposit of ruby was discovered between the Taita Hills Mts. and Tsavo National Park in 1974. In the central part of the country, in the area of Garba Tula, is the largest deposit Duse to be at monzonite dike in the extent of some kilometers and thickness up to 5 m. Here obtains crystals of sapphire in the size up to 20 cm. from dark blue before yellow painting. The occurrence of blue sapphire with manifestations of asterism and dichroism was found in basalts on the eastern bank of Lake Turkana (form. Rudolf’s Lake) in the northern part of the country, close to Lodwar. The Chimvadzubu deposit with ruby and many-colored Tanzania sapphire was found in Malawi. The deposit is located in 70 km. to the south of Nyasa Lake, near Chimvadzuli Hill, adjacent to the Mozambique border. The occurrence of dark blue sapphires with large crystals of weight up to 12 ct. was found out in alkali basalts in proximity to Tsiangugu locality in the southwest of Rwanda. Placers of ruby are exploited near Sembulule in Zambia. Mining in Zimbabwe are sapphires of different color, those with zonal distribution of coloration among them. Zonal crystals have size up to 7 cm., their color changing from cream-white in the center to blue to the outside. Black star sapphires are also derived from this country. In Nigeria the deposit of sapphire of blue, green and yellow colors is present in alkali basalts of the Kaduna Prov. It is situated to the north of Jos Plateau at a distance of 45 km. Sapphires of Nigeria, likewise those of Kenya, are characterized with dark blue and green-blue color. Well known also are sapphires in adjacent Cameroon, near Nguti Town. Star sapphires occur in placers of Congo (Kinshasa). In the South Africa in Sudimani Spruit Dist., Northern Cape Prov., there is a sapphire deposit where seen are opaque crystals of weight 152 kg. and as big as 60x30 cm., and another of 1 m. in length. In Namibia, in the Great Namaqualend area, blue sapphires are found. At the deposit Laaste Hoop corundum zonal crystal up to 6 cm. was found. In North-East Africa currently sapphire and ruby deposits were discovered, namely, Somalia – close to its northwestern border, in the Borama Dist. A deposit of ruby with green zoisite had come to light in a metamorphic rock resembling as in Tanzania. Sapphires are present in nodules of the metamorphic rock and display green-blue color on there outside surface while inside part of the crystals are blue. Localities of ruby are found in the southern part of Madagascar Is. They are called Gogogogo and Ejeda. One more deposit of ruby and sapphire is situated in the central part of the island in the Antananarivo Prov. at the vicinity of Antanifotsy. Recently four new deposits of sapphire were revealed in the south of the island. They are placed adjacent to the following settlements: Bekily, Andranondambo, Amboasari and Sakaraha. In 1996, on the northern extremity of Madagascar, near Ambilobé, discovered was a deposit of blue, blue-violet and brown-red sapphire, its crystals being up to 2 cm. long.

In 1851, in Australia the first placer of sapphire resulted from erosion of basalts were found in New South Wales: adjacent to Inverell, near Glen Innes, New England Range. The size of sapphire crystals in the placers does not exceed 2.5 cm.; they are transparent and no more than 10 ct. only rarely – up to 25 ct. The more abundant are blue, blue-green, blue-yellow sapphires; less common are yellow, green and colorless varieties. In 1870, the most important sapphire deposits were discovered over the area about 900 km.2 in the Anakie on the western offshoots of the Great Dividing Range, Queensland. Together with sapphires subordinate quantities of hyacinth are present here as well. Typically, Australia sapphire, Anakie sapphire or Queensland sapphire is characterized with different colors, sometimes very intensive, often zonal due to combinations of yellow color with green and blue. Pink and red-brown colors are rather rare. Pink-green sapphire has received its local name wattle in accordance with the color of acacia, which is also called mimosa – the state symbol of Australia. Jewelry sapphires usually do not exceed 1cm. in size, though larger crystals are there too. Deep blue color of the stones changes to pink, greenish or almost black in artificial light. Therefore, such rough material in the majority of cases is anneal-treated. Stones with silky luster and asterism through rutile inclusions, as well as crystals with alexandrite effect occur. In 1979, in the Harts Range Mts., Northern Territories, were discovered of ruby deposits with crystals up 5 to 12 cm. in size and of weight up to 5 kg. Furthermore, placers of sapphire and ruby were found to the north-east of Alice-Springs, Northern Territories. In Western Australia, at the Poona deposit ruby and sapphire occur together with alexandrite, emerald and topaz. Finds of semi-transparent ruby – barklyite, which are good only for cabochon cut, are known in placers of New South Wales and Victoria States in South-Eastern Australia. Nowadays, Australia is the main supplier of sapphires at the world market (about 75%). In addition, placers of noble corundum, star sapphire among them, have been encountered in fluvial deposits of Tasmania where weight of some sapphires is as big as 245 ct. In the southern part of New Zealand at South Is. made evident are boulders of green tourmaline-fuchsite rock of metasomatic origin with inclusions of ruby and sapphire. This rock represents a new ornamental stone with a commercial name goodletite.

In Myanmar (Burma) the most significant placers of ruby are situated in the north of the country, close to Mogo (Mogok) and Mandalay towns. They have been developed since the 6th cent. A.D. and occur not very deep beneath the surface, spreading over approximately 400 km2 . In the same area, near Möng Hsu village, a new deposit was opened in 1992. Möng Hsu ruby yielded here show a wide variety of bloody-red color – from light tints of pigeon’s blood to dark red hue of bull’s blood. In parallel with ruby there also are other gemstones suitable for cut: blue apatite, garnet, cordierite, moonstone, steel-blue sillimanite, phenakite, chrysoberyl, spinel and epidote. In Thailand the development of deposits of noble corundum has been underway since 1850, when Siam Kingdom yet existed. Its main placers are located in the southeastern part of the country in the vicinity of the Chanthaburi and Trat towns, adjacent to the coast of the Siam Bay, on the border with Cambodia. They were formed owing to weathering of basalts and contain up to 70% of gemstones reserves of the country. Sapphires ranging in color from light brown to orange-red are yield here. Mainly sapphires are yield near Manthaburi, blue and black sapphires with asterism among them. This effect characteristic of black sapphires results from abundant inclusions of fine lamellae of hematite oriented parallel to faces of apex of corundum crystals. Red ruby, but with weak luster – Lataia ruby, brown-red and green sapphires are found at the Bo Rai and Bo Wien deposits, to the East of Chanthaburi. Colorless and yellow stones from these deposits are anneal-treated and turn into golden-yellow sapphires. Rubies obtained here make up about 70% of all rubies at the world market, but are distinguished from Burma rubies by slightly yellow tint. In addition there are other areas of sapphire yield in Thailand. They are situated in the Sisaket Dist., the East of the country, and in the Phrae Dist., in the north of it. In the latter case we are dealing with the Den Chai deposit. In the west of the country, close to the Myanmar border, the Bo Ploi deposit, Kanchanaburi Dist., is placed. It has been exploited in the crust of basalt weathering since 1920. The color of sapphires here is a velvety deep blue, usually with greenish hues. Cornflower sapphires or Siam sapphires from Thailand are highly valued in England. In the U.S.A., however, dark blue stones are attributed to Siam sapphires and set less than Burma sapphires. The sapphire deposit situated to the southwest of Battambanga, near Paylin has been worked out in Cambodia on the border with Thailand since 1874. Others sapphire deposits are situated in the North of the country in the area of Rovienga – Phum-Thmei and in the northwest Thyamnop. In the southwest of Laos, Bokeo Prov., there sapphire deposit Laotian is operated and in the northwest of the country known is the deposit Houay Sy. In spite of small sizes of these sapphires, the bright-blue rough material is appreciated for its excellent quality. In Sri Lanka, since ancient times, noble corundum has been yielded in many regions – as in south-western and central, so in the eastern parts of the island. Here, among deposits bound with weathered rocks such as these situated near Ratnapura, Elahera and in the basin of the Kalu Ganga River, the richest placers of ruby, sapphire and blue spinel occur over the area of about 2000 km2 . Typical of these deposits are many-colored sapphires. Among them is blue Ceylon sapphires with mottled distribution of coloration resembling the color of seawater, padparadschah, strawberry-colored rubies, rubies and sapphires with asterism, sapphires with alexandrite effect and milky-white corundum. The great bulk of Sri Lanka rubies exhibits manifestations of asterism and is marked by bluish or brownish coloration. Sapphires crystals range up to 500 ct. In 1974, there were found two sapphires: a blue crystal of weight 114 ct. and yellow one 300 ct. Blue and blue-green sapphires are yielded on the Indo-China Penin. in South Vietnam. In North Vietnam, in proximity of the Chinese border, the Mock Yên and Kay-Chau deposits with ruby and light red or purple sapphire were discovered in 1983. They are situated in Yên Bái Prov. close to L’c Yên and compare well with Myanmar deposits. Here, corundum is encountered in marbles together with spinel, garnet and tourmaline. In China occurrences of sapphires and rubies are located in the following provinces: Heilongjiang, Hebei, Sichuan, Jiangsu, Shandong, Fujian, Yunnan Prov. in the Ailao Mts. and on Hainan Is. in the South China Sea. Sapphires of China resemble these of Australia: they are ink-blue up to greenish-blue and do not exceed 1 cm. in size. Crystals of ruby of the same size were found in the east of Xinjiang-Uygur Autonomous Region in Zizhou locality. In Japan on Shikoku Is., Prefecture Ekhime, green ornamental ruby-zoisite rock has been identified. It is akin to anyolite from Tanzania.

The most ancient ruby deposit is known in India, Orissa State, near KÇlÇchÇndi. It is connected with a contact zone between gneisses and ultra basic rocks. Other occurrences of noble’s corundum are in Rajasthan State, close to Djanvali; in the Madhya Pradesh State, near Pipr; in Maharashtra and Tamil NÇdu States. In Tamil NÇdu on the area 70x70 km in area Karur-Kangijama in pegmatites and gneisses, are numerous deposits of a ruby and sapphire, and also alexandrite, sunstone and moonstone, garnet, cordierite, rock crystal and amethyst, and also topaz and tourmaline. Biotite-sillimanite gneisses containing opaque rubies called Alipur stone are found in the Karnataka State, of the Mysore Town area. Their large translucent crystals of size up to 5 by 12 cm. show asterism and are good only for producing of collection balls and cabochons of weight up to 100 ct. Placers, where ruby of pigeon blood color has been worked since 1880, are located in the north of the country, in the Jammu and Kashmir State (disputed area), near by Sumdjan, on the Bkhutna River. At the same area, in the Zanskara Mts., velvety cornflower-blue Kashmir sapphires are discovered and a start has been made on their exploitation. At these deposits, evidence is made in plagioclasites which had been subjected to kaolinization are crystals of sapphires measuring 7.5x12.5 cm., the crystal of 998 ct. is among them. Velvety luster of sapphires is conditioned by the availability of tiny gas-liquid inclusions and finely dispersed rutile. There is a number of ruby deposits connected with huge lens of marble in gneisses exposed in the valley of the Hunza River, near Gilgit. The average content of gemstones in the rock reaches 20 gm./ton and ruby crystals here are of weight up to 1-2 ct. In 1982 the detected to the northwest of India – in Nepal, the Tanledjung Dist., to the North of Kathmandu. In 1960, in Pakistan, the Timagrara Dist., close to the north-western border with Afghanistan, over than 10 ruby deposits in marble series were discovered. At high content of ruby in the rock, the size of its crystals does not exceed 15 mm. Pakistan rubies are mainly light red, often weakly transparent. Placed likewise in marble is the ruby deposit Jegdalek found in Afghanistan at the distance of 50 km. to the east of Kabul. The color of ruby here ranges from dark red to light red; their crystals length is up to 10 cm.

Brazil ranks the first among other countries of American continents in abundance and quality of ruby and sapphire deposits that are mainly related with pegmatites. The largest deposits are located in the Bahia State: in the Citiu da Jiboja Dist., near Barra de Ingedinjo and in the vicinity of the following cities – Nee, Jacobina, and Kapim Grosso. Rose corundum was developed at the Lagedino deposit. In the Minas Gerais State, occurrences of ruby and sapphire are known close to Triangola Mineiro, and near Malacacheta, in proximity to Bereikh Datus and Diamantina, as well as adjacent to the of Rio Sapucaí. In the Goiás State relatively large opaque crystals of Brazil sapphire are yielded at the Santa Teresinha and Porteiras. Other sapphire occurrences are placed in the Mato Grosso do Sol State – in the Rio Coksim area, and near Jauru; in the São Paolo State – close to Ithaca; in the Santa Catharine State – by Barra Velha. The deposit of multicolored sapphires, sapphires with alexandrite effect among them, was discovered in southwest Colombia, Rio Mahio region, Cauca Dept., in 1985. The size of tabular sapphire crystals here is up to 3 cm. across. The biggest faceted stone received from here, had weight of 16 ct. There are no considerable deposits of noble corundum in the U.S.A. Gold placers containing also sapphires were disclosed in the basin of the Missouri River, Montana State, in 1865. They were worked for a long time. Sapphires incidentally extracted there ranged in their color from blue to green, sometimes being two-colored. Here and there crystals showed silky reflux, slight asterism and clearly defined alexandrite effectblue alexandrite. The size of their crystals was not over 1 cm. The small ruby occurrence Covey-Creek is known in North Carolina. Rubies and sapphires were extracted at the Count-Valley deposit close to Franklin. The shape of ruby crystals is flat; their size chiefly is not large – 163 ct., at most. In the faceted they seldom are more than 2 ct. There are the sapphire deposits Yogo Creek and Yogo Gulch in the Judith-Basin Co., Montana. They are related to a lamprophyres dyke 2-6 m. thick, extending for 8 km. It has been developed since 1886. Constantly extracted here are Montana sapphires and Yogo sapphires characterized by bright cornflower-blue color that does not change in artificial light. Cut gems made of these rough materials usually do not exceed 1 ct. Crystal sapphire “The big firmament” had weight of 24 ct. and from it the faceted stone in weight of 12.54 ct. is received. Two other – French Bar and French Creek deposits are known in that State. In 1989 jewelry sapphires were found in alkali pegmatites in Canada, near Bancroft. Crystals of the mineral here are as big as 1.5 by 5 cm., but because of too insignificant quantity of the materials suitable for cut, mainly collection stuff is produced here. A crystal of opaque corundum of weights 27 kg. has occurred at the Craigmont mine, Renfrew Dist., Ontario. On the Baffin Island in marble the deposit of sapphire of jeweller quality near Kimmirut is found.

Unique Findings. According the statistics, the frequency of findings of large sapphire crystals is higher than that for ruby. Compared with diamonds, there is the following correlation: 300 diamonds of weight more than 200 ct. have been found for 100 years (from 1870 till 1970) and beyond 10 rubies of the same weight occurred during that time. Therefore, even rubies of weight 40 ct. were considered as unique ones (App. 3). The list of unique crystals and cut rubies and sapphires is rather long; it is partially given in App. 4.

Ruby. Of crude stones worthy of mention is the crystal of Burma ruby kept by the British Museum, London. The gemstone is 12 cm. length and possesses weight of 690 ct. The high-quality stone of weight 496.5 ct. found in Myanmar (Burma), Mogok Dist., and called “Council of State Ruby” is marked as national property. In 1890, two large rubies were extracted at the same deposit: one is of weight 312 ct., another – 410.6 ct. After the cut of the last one, two gems of weight 70.8 and 46.1 ct. were produced. At the same place, the transparent ruby crystal of deep color and weight 42 ct. was found in 1918 and in 1928 there was gotten another gemstone – of weight 150 ct. One more unique ruby from that district is exhibited at the Nat. Hist. Museum, Los Angeles. Its weight is 196.1 ct. In 1999, a jewelry quality ruby crystal from Myanmar of weights 3,500 ct. was demonstrated at the exhibition of gemstones in Tucson, the U.S.A. The most beautiful of crude rubies are the following: the semi-transparent crystal "Edward’s Ruby” revealed in India in 1828, its weight being 167 ct.; a Burma ruby of weight 150 ct. and a similar stone of weight 77 ct. discovered in 1899. In 1990, in Mogok is found a crystal of a ruby in weight of 504,5 ct. It has received the name “Navata” has weight of 496,5 ct. Also it is kept in Rangoon. In 1994, is found in Myanma low quality a crystal of a ruby more than 30,000 ct. From it is made cabochon with asterism in weight of 6,465 ct., named “Stellaire remarquablee”. The largest crystal of a ruby is “Devil’s Eye” in weight of 66,550 ct. The opaque star ruby of weight 2,967 ct. was found on Sri Lanka Is. in 1934. The largest jewelry ruby of weight 10,800 ct. was discovered in North Vietnam, Yên Bay Prov., in 1999. It was valued in about $9-11 million and was retained unwrought, in the form of natural crystal as the state property.

Sapphire. The biggest opaque sapphire of weight 150 kg. and size 60x30 cm. was recently found in South Africa, in Sudinami Spruit, Northern Cape Prov. A crystal of opaque corundum 1 m in length has occurred in the same region. Previously the next sapphire crystals were considered to be largest: a stone from Sri Lanka of weight 40.3 kg. and size 20x50 cm. and one of size 2.5 by 4.5x14 cm. and weight 18 kg. The last one was found in 1986, from which the stone in weight of 188 ct. was faceted. Next in importance is the sapphire of weight 17.97 kg. extracted on Madagascar in 1996. The third one is the largest opaque crystal of sapphire obtained in Myanmar (Burma) in 1966. Its weight is 12.6 kg. (63,000 ct.) and size – 60x17 cm.. In 1999, a description of a jewelry sapphire found on Madagascar was published. The stone’s weight is 8,045 ct., and in 2,000 there have found an opaque crystal in weight of 17.97 kg. (89,950 ct.) has received the name “Sapphire of millennium”. The sapphire of the weight of 6,454.5 ct., measuring 10.8x8.4x5.1 cm. was revealed in Thailand in 1977. Mention should be made of the poorly rounded sapphire of weight 4,230 ct. from Myanmar (Burma). The sculptural portrait of “A. Lincoln” of weight 1,318 ct., was cut in the U.S.A. from a large semi-translucent sapphire measuring 2,302 ct. The stone was extracted at the deposit near Anakie in Australia in 1935. Of the similar nature is the portrait of “D. Eisenhower” created on a black star sapphire in 1953. Weight of the starting material was 2,097 ct., after cut the product measures 1,440 ct. The semi-transparent sapphire with a portrait of “G. Washington” is of weight 1,056 ct. The next unique star sapphire of weight 1,905 ct. was originally sold for $10 at the Arizona gemstone exhibition in 1987. Later on, it was evaluated at $2.28 million. After cut of the stone two gems of total weight 1,250 ct. were produced. Among unprocessed jewelry stones, mention may be made first of all of two sapphires from Myanmar (Burma). One of them measuring 951 ct. was in a king’s treasury-house in 1827; the second crystal of weight 958 ct. was found in 1929 and called “Treasure of Jungle”. Nine gems were cut of it. Furthermore, known is the crystal of blue sapphire of weight 3,100 ct. from the Baruta mine, Northeast Zimbabwe. In Australia, Queensland State, in 1946 the crystal of yellow sapphire of weights 215.5 ct. was found at the Anakie mine and yellow-green sapphire of 162.26 ct. – at the Ruby Vale deposit. “Siam sapphire” of rare beauty with weight of 125 ct. was disclosed in the southeast of Thailand. The largest crystal of opaque corundum of 68x30 cm. and weights of 152 kg., is found in South Africa. It is in the museum of Pretoria.

Synonyms. General for corundum – Adamas, that is by hardness in Gk., See Pliny the Elder | Siderites adamas | Aloxite | Corindon, Fr., obs. | Corunduvite, obs. | Demantspath, Germ. | Harmophane, obs., from the Gk. “harmos” – jointing and “fanos” – clear, because of good parting | Jachont (jachonite), obs. Russ., from Arabic – jacut, jagut,; Pers. – yakund, Gk. – yaksintos, Lat. – hyacinthus | Hard spar.

Star ruby and star sapphire – Asteria (asterix) from Gk. “aster” – star | Asteriated corundum | Star jachont | ~ sapphire: almandine ~, amethyst ~, black ~, gray star ~, ruby star ~, yellow star ~. | Victory stone | Star topaz | Zvezdovik, obs. Russ.

Girasol, from Ital. “girare sole” – turning the sun – Opalescent chrysolite | Chatoyant corundum | Pearly corundum | ~ girasol: jachont ~, oriental ~, ruby ~, sapphire ~. | Opaline | Oriental moonstone | Oriental sunstone.

~ cat’s-eye: corundum ~, oriental ~, ruby ~, sapphire ~, topaz ~. | Chatoyant jachont.

Ruby – Anthrax, obs. | Carchedon anthrax | Carthago anthrax | Carbuncle, anc. name of red gemstones | Carthedon carbuncle | Haramant carbuncle, See Pliny the Elder, after a Garamant tribe (Berbers) in North Africa | India carbuncle | Carthago | Red jachont | Red jacut | Likhnis, from Gk. “likhnis” – candle, obs. | Manikya, obs., Hindu., | Ratnaraj, Sanscrit – king of precious stones | Ratnanâyaka, Sanscrit – leader of precious stones | Pigeon blood ruby | Sapphire ruby | Alipur stone after the place of the finding near Alipur, close to the town of Mysore, India | Carthago stone.

Sapphire – Amethystus, obs. | Blue jacut, obs. | Nila – blue, Sanskrit, obs. | Samphire | Samphoulo, obs. | Sanphire, obs. | Saphire, obs. | Sapparite, obs. | Fancy sapphire | Gray sapphire | Occidental sapphire | Shaphire | Smiris, obs.

Colorless – Oriental diamond | Colorless jachont | White jachont | Geuda sapphire | Topaz-sapphire | White sapphire.

Pink – Balangus, obs. | Viennese hyacinth | Ceylon ruby | French ruby | French color ruby.

Yellow – Yellow jachont | Yellow jacut | Indian topaz | King topaz | Noble topaz | Oriental topaz | Viennese topaz.

Rose-orange – Purple jachont | Padmarâgaya (padmarâga), Sanscrit – red as the lotus | Padparadschah (padparaja) | African padparadschah, after the place of their finding | Sapphire padparadschah.

Red-brown – Chrysolite hyacinth | Oriental hyacinth | Chantaban ruby, after the place of the extraction in the vicinity of Chantabana Town, Myanmar | Oriental ruby | Siam ruby, from Myanmar, after the old name of the country Siam | Vermeil ruby | Hyacinth sapphire | Umbalite sapphire, after the place of its finding on the Umba River, Tanzania | Vermeil sapphire | Sealing wax sapphire | Oriental vermeil.

Green – Chlorophane, from Gk. “chloros” – green and “phaneistay” – to change, because of color change on annealing | Chlorosapphir | Oriental chrysoberyl | Oriental chrysolite | Orientalemerald | Viennese emerald | Western emerald | Green jachont | Oriental peridote | Pyrosmaragd | Chrysolite sapphire.

Blue – Blue alexandrite | Oriental aquamarine | Bogus (bagus, bous), the Old Russ. name of blue gemstones | Cyanus – “cornflower”, obs. | Cyprian blue diamond | Oriental hyacinth | Azure jachont | Cornflower-blue jachont | Jacut | Blue jacut | ~ sapphire: alexandrite ~, Anakie ~, after the place of the occurrence near Anakie, Australia; aquamarine ~; indigo ~; Inki ~; Inverell ~, after the trade center in Inverell city, New South Wales, Australia; lynx ~; man’s ~ (dark); Montana ~, from the Montana State, the U.S.A.; oriental ~; women ~ (light).| Tausiny stone, the Russ. name | Télésie, from Gk. “teleyos” – perfect | Zafir (zaffiro), the Old Germ. name.

Violet – Oriental almandine | Bengalian amethyst | Oriental amethyst | Apirote | Oriental corundum | Oriental hyacinth | Violet jachont | Purpursapphir | ~ sapphire: almandine ~, amethyst ~, purple ~, ruby ~, violet ~. | Smirgel, obs. | Sintholite, vanadium-rich | Violet.

Polychromatic – Watermelon sapphire.

Quality improvement. The method of quality improvement of corundum by ignition has been known since ancient times and was described by Pliny the Elder and in the “Stockholm papyrus”. Formerly the purpose of discoloration was to imitate diamond. Currently available methods of quality improvement of minerals amounting to the following approaches: a) transformation and intensification of color, b) clarification of opaque crystals with structure change and creation of silky effect and asterism, c) flaw healing, d) joint of synthetic crystal layer with use of flux method, f) film cover of cut stone surface to intensify its coloration. In the course of corundum annealing undesirable tints are eliminated and color becomes brighter. This method has found wide use in quality improvement of Australian sapphires possessing deep bluish-green color. Blue color can be regained during ignition of pale and colorless sapphires for 6 hours in the presence of nitrogen at the temperature of 1,720°C. Under analogical conditions brown and violet sapphires grade into red ruby at the expense of change of valence of chromophors admixtures. Yellow sapphire would begin to take on deep yellow or orange color through the loss in hydrated water at annealing. Blue sapphire from Sri Lanka turns to yellow one on annealing at the temperature up to 400°C. The method of ionic implantation of sapphires represents ignition for 1-2 days of cut stones at 1,800°C in a charge of (Al2O3+6Cr2O3+22TiO2) with addition of oxides of iron, Calcium and strontium that results in diffusion of these admixtures into a crystal framework and causes the appearance of steady coloration: red, orange, bright blue, in the outer layer of a stone (up to 0.1 mm thick). Artificial transformation of color of natural sapphires makes influence on their price and calls for specification of the used methods. For instance, it is necessary to mark: diffusion treated sapphire by the method of diffusion. As corundum ignition leads to irreversible, stable in time consequences, the Gemological laboratory of E.J. Gübelin in the U.S.A. had elaborated a scale of thermal improvement including 6 categories according to the grade of healing of flaws and to the quantity of residual products in them. The scale may be used as for a ruby, and sapphire. In connection with the greater value of padparadschah sapphire at the world market in recent years, their improved varieties are very popular. They are widely produced by ignition and ionic implantation of pink sapphires from new deposits situated on the south of Madagascar.

In 1976, the opportunities of enlightenment of milky-white corundum, or geuda sapphires by the way of ignition in a sodium borate solution at 1,550-1,900°C were opened. Rapid or gradual cooling will bring into existence either stable red or blue color. This procedure is connected with a change of a crystal structure and recrystallization of admixtures and inclusions. But as it takes place, the output of jewelry rough material does not exceed 25%. In the same way, either creation or elimination of silky effect or asterism in corundum crystals is achieved. Welding of flaws and caverns with use of resin, glass and plastic is also provided by anneal treatment. The similar effect is obtained by applying of methods of synthesis on seed-plate, when a built up layer masks defects of pale-colored seed-plate. In appearance it resembles corundum processed with use of diffusion. Thermal treatment leads to formation of disk-shaped flaws, so called “fire signs” well distinguishable under the microscope. In addition, gas-liquid inclusions in corundum disappear, contrasts of zonal coloration increase, pleochroism decreases. Recent years there are trends toward the increased usage of methods of coating of fine noble metals films on surface of cut stones. Colored plastic covers are popular as well. So a cabochon of leucosapphire with asterism, being covered with red plastic, shows up as asteriated ruby. Gamma radiation, which induces unstable reddish-yellow coloration like that typical for padparadschah, is also used as a method of improvement of colorless or pink sapphires. In parallel with new methods of quality gemstones improvement, the old ones still remain valid. The case in point is the method of oil treating with addition of dyestuffs.

Cut Gems. Ruby was always believed to be the main stone in India. It is called “Ratna Rajah” that means “Queen of Gemstones” in Sanskrit. A considerable amount of unique gemstones was collected in the treasure house of the Great Moguls and Sasanides during the long period of development of noble corundum deposits in the East. Among them were the “Akbar Shah’s Ruby” – 200 ct., “Anka’s Ruby” – 468 ct., “Jabaliya’s Ruby” – 669 ct. With advances in trade communications rubies and sapphires were coming from the East to Ancient Egypt, Greece, Rome and later to Europe. In Ancient Rome ruby was considered as the most valuable stone. Of unique jeweler’s work of art of the Renaissance, mention should be made of a statuette-copy depicting Venus of Milo cut of jewelry sapphire. Its height with a pedestal from ruby is 8.75 cm., weight – 100 ct. In the former times the statuette belonged to the Duke Charles von Braunschweig and was bought at an auction in Geneva by the Prince N.B. Jusupoff in 1874. The transparent blue “The Great Sapphire of Louis XIV” possessing weight of 135.80 ct. and cut in the shape of an orthorhombic prism is kept in the Nat. Hist. Museum, Paris. The stone was suggested to be brought from Bengali (India), however, on the evidence derived from the inclusion investigations. Its origin from Ceylon (Sri Lanka now) was determined. The treasure-house of Louis XVI also contained the “Polish Eagle”, its body being made of a large cut hyacinth bordered with 150 rubies and brilliants. Ruby is one of main gemstones among ambassadorial gifts sent by the ruler of Iran Nadir-shah to the Russian Tsar in 1739 and placed in the State Hermitage, SPb. now. From 1,000 to 2,000 rubies and emeralds can be counted in the inlay of gold jugs being among the gifts. And there was adorned with 3,163 stones decorative table-top of the size of 23.7 cm. across. The list of them includes 1,762 rubies, 1,017 emeralds, 380 pearls and 4 diamonds. Usually rubies and sapphires, having been brought to Europe, were collected by royal houses. Decorated with them are signs of state power: crowns, scepters, thrones, coronation finery and orders. Large rubies and sapphires in these jeweler’s work of art eclipsed the luster of brilliants. Such is the case for the “Crown of Charles IV” of the King of Bohemia. In the 14th cent. it was done anew from a wreath of St Wenceslas – the enlightener of Czech. Its decoration includes: tourmaline of weight 250 ct., measuring 39.5x36.5x14 mm; two Ceylon sapphires of weight 330 and 280 ct.; and 17 large sapphires in the shape of cabochon of weight exceeding 200 ct. In addition there are a big cameo; 45 Badakhshan spinels, the largest of them possessing weight of 100 ct.; 26 emeralds from Egypt; 20 pearls, aquamarine and rubellite. “Crown of Louis XV” of the King of France was made in 1722. It glitters already with cut sapphires and rubies. The wonderful “The Stuart’s Sapphire” and “St Edward’s Sapphire” are mounted in the Imperial crown of Great Britain. Among the unique jewelries of the 19th cent. there is also the wedding gift of Napoleon Bonaparte to his fiancée Mary-Louisa. It represents a complete set of decorations with rubies and brilliants: crown, tiara, comb, earrings, necklace and bracelets. The French firm “Chameau” represented the work in 1811. It had taken more than 120 cut rubies, half of them measuring large size. An excellent clasp decorated with 84 Burma rubies in the shape of cabochons, each being of weight exceeding 11 ct., is available in the treasury of Iran. The collection of gems of the State Hermitage, SPb., contains the cameo from the Netherlands (15th cent.) cut on a sapphire and representing an image of angel’s head. The cameo dimensions are 1.5x1.2 cm.

Among modern unique jeweler’s work of art are ruby necklace by the French firm “Van Cleef & Arpels”. It is inlaid with 1,444 rubies and 27 brilliants. Likewise effective is the ruby necklace “Gucci” produced by the U.S.A. firm of the same name. Used there were 83 oval ruby cabochons of the total weight as large as 90,000 ct. They are framed with 456 brilliants of the overall weight 10.25 ct. The platinum brooch “Shrimp” decorated with 6 rubies and 53 brilliants, to the total value of $400,000, was displayed for sale in the U.S.A. in 1998. The peculiarity of the jewelry is a pulsing glowing of the rubies in the rhythm of systoles of a woman wearing the decoration. The rubies glowing are provided by light-emitting diodes mounted in the brooch setting. Two brilliant brooches with large sapphires, one of them containing a gem of weight 337.66 ct., while another – 65.8 ct., are described among unique jeweler’s work of art with sapphires in the book by John Traina “Extraordinary Jewels” (1997). A picture of a platinum necklace with 44 large sapphires of different colors and with 965 small brilliants is given here too. In the same book also mentioned does the sapphire garniture by the firm “Van Cleef & Arpels” comprise a ring with a sapphire of weight 25 ct., earrings, a brooch and a necklace consistent with a style. In all, 49 violet-blue sapphires are used in the set; the majority of them are variable in their weight from 8 to 20 ct. and only 16 stones approximate to 1 ct. each. The sapphires in this garniture are surrounded with 630 brilliants. A further unique garniture consisting of a necklace, a bracelet, earrings and a ring is discussed in the same book. All these things are made in the shape of a chamomile where yellow sapphires and petals are depicted with the use of brilliants in combination with blue sapphires. In the whole, there are 43 sapphires in the set, 22 among them are large.

Series of carved images on large translucent sapphires were created in the U.S.A. The images of three presidents are dealt with: “D. Eisenhower” (2,092 ct.), “G. Washington” (1,997 ct.) and “A. Lincoln” (1,318 ct.). In 1980-s this series was supplemented with the image of “M. L. King” (3,294 ct.) created by the Russian artist stonecutter V. V. Konovalenko. The blue sapphire of 31 ct. cut in the shape of heart and correspondingly called “Blue Heart”, is available in the Smiths. Inst., Wash. The largest of cut rubies known as “Bell of Victory” with weight of 8,500 ct. and 14 cm. long is in a private collection in California. There is the tabular “Persian Shah’s Ruby” in the collection of the Teheran treasury. Its weight is 175 ct. In the early 20th cent., the former owner of the famous diamond “Koch-I-Noor” Runjit Sing possessed a large ruby that had the size of half a hen’s egg and was evaluated at £12,5 bbl. The biggest star ruby cabochon of weight 6465 ct. and dimensions 109x90.5x58 mm is in New York. The two large cabochons of star ruby “Rajahratkhna” (2,475 ct.) and “Neelandjakhi” (1,370 ct.) belong to India. The latter one, with a double 12- ray star, measures 5.08 by 7.62 cm. Of cut work of art worthy of mention is the gem “A Good Samaritan” from a private collection in the U.S.A. It measures 3,400 ct., being cut of a piece of translucent Mozambique ruby of weight 4,500 ct. At the present time, a major part of high-quality rubies and sapphires arrives for cut in Bangkok, Thailand; in Israel; in Idar-Oberstein, Germany; in Japan – mainly starstones.

Rubies and sapphires are indispensable attributes of the Tsar’s regalia in the Old Russia. They can be seen in crowns, scepters and decorations of thrones. Ruby was the favorite gemstone of Ivan the Terrible and Peter the Great, who kept it as a talisman. The unique Ceylon sapphire of weight 250.18 ct. decorated the state power symbol – so called “Orb” or “Globe” is reserved in the Diamond Fund of Russia (D.F.R., Moscow). The fund also stocks the splendid diamond garniture with sapphires comprising earrings and an aigrette (Fr.) – a pin for hair-dress of a sort. The aigrette measures 7.5x7.5 cm., earrings – 9.5x3.8 cm. In order for such decorations to be made, in 1760-s 40 sapphires, more than half of them being large, were used. Another set with rubies and brilliants kept in the D.F.R., Moscow is no less effective. It was created at the same time and consists of earrings measuring 4.2x6.3 cm. and a brooch with a pin of size 4.9x4 cm. It was necessary to obtain 34 rubies, mainly large, to produce the decorations.

Auction prices of unique stones can be inferred by the following examples. In 1977, at the auction Christie’s in Geneva a sapphire of weight 42.62 ct. was sold for $216,534, which is $5,080 per ct. In 1976, $31,700 per ct. was paid for high-quality rubies. The record price – $228,252 per ct. was paid for the “Mogok Ruby” at the auction Sotheby’s in New York in 1988. It was made in the shape of a small pillow and had pigeon-blood color and weight of 15.97 ct. In 1996, at the exhibition in Rangoon, a ruby of weight 21.77 ct. was evaluated in $1 million. The maximum price of sapphire was $2,791,723. It was paid for the stone of weight 62.02 ct. in a ring with a brilliant on the auction in Switzerland on February 20, 1988. The sapphire of weight 66.03 ct. from Rockefeller’s collection was evaluated in £579,300 in 1980. In 1996, at the exhibition in Rangoon shown was the sapphire cabochon of weight 75.02 ct. It was evaluated in $200,000. The price of stones may vary with time. The price of bright blue Kashmir sapphire of weights 44.98 ct. was £75,000 in 1974, while in 1971 they paid only £6,000 for a stone of the same kind and of weight 66.03 ct.

Legends. Indian magi called ruby a clot of hot dragon’s blood. Rubies were considered to provide people with power and to have a profound impact on them. To magus opinion, clear, homogenous and transparent ruby is related with karma of strong and imperious persons maintaining their power. According to a popular Indian superstition, ruby used as a talisman imparts lion’s strength, eagle’s fearlessness and snake’s wisdom to its owner. A ruby amulet strengthens mind and heart, sends away melancholy, criminal desires, obscene thoughts, as well as protects against devilment, terrible dreams and serious illness. An owner wears it on a forefinger of his left hand. Judging from the Bible, ruby is a main stone in pontiff’s breast decoration. Church ordained it to Philip the Apostle. Astrologers think ruby a fortunate stone for people born under the Mars in the constellation of the Leo. It is good only for these appertaining to fiery signs – Aries, Leo and Sagittarius. A ruby is the national gemstone of Myanmar (Burma).

In the ancient times sapphire symbolized the firmament and was appreciated as a stone of immortality and chastity, wisdom and enlightenment. In Egypt and Rome sapphire was considered to be a stone of truth and justice. Romans dedicated sapphire to the supreme deity Jupiter. They believed that it guarded against anger and fear, cleared soul, and gave inner concentration during prayers. Sapphire is wholesome for kind and clean people who achieved high spirituality. Therefore it is accepted as a stone of ecclesiastics, in particular of Andrew the Apostle. The Catholic Church prescribed its bishops and cardinals to wear sapphire on a right hand, as a token of the right to bless and manage justice granted by Heaven itself. Sapphire damps their wild passions and directs their thoughts to the higher spheres of spiritual life. As a talisman, sapphire is favorable to business, aids to earn love, and promotes kind undertakings, assists travelers. A sapphire amulet protects from treachery and slander, rage and dread, helps to avoid shipwrecks. It is necessary to wear such a sapphire on a ring finger. As the Bible says, sapphire is the fifth stone of pontiff’s breast decoration. Astrology considers blue-light blue sapphire as a stone of people born under Jupiter in the constellations of Sagittarius and Aquarius, rose sapphire – in the constellations of Ram and Taurus, yellow stone – of Gemini and Virgo, orange one – of Balance. Noble corundum is the national stone of Sri Lanka. A sapphire is the official emblem of the Montana State, the U.S.A.

Synthesis. In 1880, experiments were run on sintering caking of natural ruby to produce stones of weight up to 10 ct. Those experiments preceded synthesis of corundum. Stones resulting from them are known as Geneva ruby or reconstructed rubies. In 1892, O. Verneuil devised new methods of a technique for ruby synthesis without crucible, in the flame of burner. Soon later the method had received wide acceptance. Since 1947, the American firm “Linde” has produced blue, red, white and black Linde synthetic star corundum just by this method. synthetic Shinna ruby has been turned out in Japan since 1984. Rubies grown in burner flame are exemplified by curvilinear zones and by presence of gas-bubble inclusions. These features permit gemologists to determine unequivocally the crystals originated in such a way. Different trace elements in corundum are responsible for their coloration: the presence of copper gives golden color, manganese – pink one, vanadium – purple color that changes depending on nature of light; cobalt gives gray-green color, nickel – yellow, iron – gray, titanium – yellow, chromium plus vanadium – blue up to red, cobalt plus vanadium – pale-blue to red, cobalt plus chromium – chestnut, iron plus titanium – blue-green. Admixture of V2O3 induces alexandrite effect in synthetic corundum. The presence of oriented inclusions of rutile in rubies and sapphires initiates asterism after supplementary annealing. Implantation of cobalt into synthetic corundum under the temperature of 1,300°C with following annealing leads to light blue color, because of the appearance of spinel, in epitaxial joint with corundum.

To provide a material more resembling natural ruby the method of flux, or of synthesis from solution in the melt of lithium molybdate, was used. In 1965, in such a way, ruby crystals of the size of 4x4x1.2 cm. were manufactured by cooling of the solution on seed-plate. Since 1968, this method, as well as certain of its modifications, has been used by a number of firms producing raw jewelry material. It has reflected in the names of synthetic corundum, such as following: Gilson synthetic ruby in Switzerland since 1975; Lechleitner synthetic ruby in Austria; in the U.S.A. they have been Chatham synthetic ruby in San-Francisco since 1959; Ramaura synthetic ruby in Los Angeles, California, since 1983; Kashan synthetic ruby in Houston, Texas, since 1968. The latter one is also known as Ardone synthetic ruby after the firm name.

The procedure of drawing of crystals out of melt proposed by G. Czochralski in 1918 came into use after a start had been made on the application of corundum in laser technique. Industrial synthesis of more homogenous crystals, jewelry material – specifically laser synthetic ruby, among them, was provided in such a way. The largest weight of rubies obtained by Czochralski’s method achieved 4 kg. and leucosapphire – 10 kg. In 1970, the Japan firm “Kyocera” (Kyoto Ceramics Co.) produced synthetic ruby, asteriated or star synthetic ruby and orange corundum with the commercial name Inamori synthetic ruby, or Crescent vert synthetic ruby. The method of zone fusion was a new success in the field of corundum synthesis. It was mastered in 1983 by the Japan firm “Seiko” for production of ruby and orange sapphire known under the commercial name Bijorev synthetic ruby. In 1980, in Austria Professor Knishka fabricated Knishka synthetic ruby, using the procedure of spontaneous crystallization from melt. In such a way during half a year he grew a prismatic ruby crystal of weight 382.5 ct. and later on, in 1987 – one of weight 1,100 ct. That method was used also in Austria in 1983, when I. Lechleitner created synthetic ruby and blue, yellow, violet and pink sapphire on seed-plates of synthetic corundum. In the U.S.A. obtained by flux method without seed-plates, so called created synthetic ruby is presenting the top-quality product that bears the great similarities to natural ruby. Therefore, for ease of diagnostics, it contains an admixture initiating orange luminescence in U.V.-rays. The hydrothermal method of synthesis of ruby and subsequently of sapphire was mastered the most recently – in 1990-s. The distinguishing features of the minerals obtained in such a way are specific inclusions in forms of knags and black “bread crumbs” well seen under the microscope. In 1990-s, also mastered is crystallization of synthetic corundum from low-grade natural materials by Czochralski’s method.

Synonyms. Corindite, commercial name | ~ synthetic corundum: Chatham ~, after the firm in San Francisco, the U.S.A.; Lechleitner ~, after the firm in Australia; Linde ~, after the firm in the U.S.A.; Seiko ~, after the firm in Japan | Diamondite – varieties of seven colors are produced in the U.S.A. | Thermocorundum. Colorless – Arabian magic diamond | Scientific diamond | Corundolite | Diamonette | Diamonflame | Vega gem | Vespa gem | Walderite | Zircolite.

With alexandrite effectAlexandrine | Inamori synthetic corundum | Syntelit, Germ.

Synthetic ruby – Orsital, produced in Germany in 1960-s. | ~ synthetic ruby: Fremy ~, after the name of the Fr. chemist inventing the method; Geneva ~; Kashan ~, after the firm from Houston, Texas, the U.S.A.; Knishka ~, after the author’s name, that is P. Knishka from Austria; PK ~, after P. O. Knishka; Ramaura ~, after the firm from Los Angeles, the U.S.A.; Verneuil ~, after the author’s name.

Synthetic sapphire – Iron-titanium synthetic sapphire | Knishka synthetic sapphire | Linde synthetic sapphire, after the firm in the U.S.A. | Optronic synthetic sapphire, produced by the Fr. firm “Ruby syntetique des Alps” | Synthetic star sapphire. Rose – Damburite | Rose de France, Fr. | Rose kunzite | Rosaline | Scientific topaz | Synthetic topaz. Yellow: – Danburite | Diamondite | Synthetic hyacinth | Madeira topaz | Palmeira topaz | Synthetic gold topaz. Green – Amarillas | Zirctone. Blue – Hope sapphire | Stone of hope (hope stone). Violet – Ultralite | Violet | Violite.

Similar Gemstones & Imitations. Spinel bears the closest approach to ruby and sapphire. This is true for color and general properties. The only distinction is the optical isotropy of spinel. Of other gemstones confused with ruby can be garnetspyrope, rhodolite and almandine, red tourmaline – rubellite, red beryl from Utah, the U.S.A., and red zircon. Pink topaz looks like pink ruby from Sri Lanka. Resembling blue sapphire are benitoite, cordierite, blue zoisite - tanzanite, blue tourmaline – indicolite, aquamarine, blue topaz and blue zircon. The most ancient imitation of ruby is red glass dyed with iron, copper, or gold admixtures. In the antiquity, cobalt glass was used for imitation of sapphire. More recently, the fabrication of doublets from garnet and glass, or garnet and blue glass was started. Later on, imitations from Verneuil synthetic ruby had received wide recognition. Till nowadays, doublets of natural sapphire or ruby with their synthetic analogs are popular in Thailand. Cheaper imitations from synthetic quartz and cubic zirconia (phianite) are even widespread there. To produce an imitation of asteriated ruby, a star is to be engraved on a plate from synthetic ruby. Such a stone, being cut, is called fortune star. Synthetic rubies are subjected to annealing and then rapid cooling for formation of flaws that are filled up with fast hardened liquids. Imitations of such a type resemble natural ruby in appearance.

 

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