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73-772: Bokeo was named after the sapphires mined in Houayxay District. A stele that is dated 1458 is found in the Wat Jom Kao Manilat, a pagoda built in 1880 of teak in Shan architectural style . Fort Carnot , a historical artifact of the French colonial empire , now belongs to the Lao Army. The province was created in 1983, when it was split off from Luang Namtha province . In 1992, Paktha and Pha Oudom Districts were reassigned from Oudomxay province . In

146-643: A catfish , the largest freshwater fish in the world, is found in the Mekong River. It grows to 3 metres (9.8 ft) in length and could weigh up to 300 kg. It is an economic resource as it commands a high market price. The flesh of this endangered fish is considered a delicacy. There are several temples in the capital city of Houayxay, including Wat Chamkao Manilat, Wat Jom Khao Manilat (constructed in 1880), Wat Thadsuvanna Pkakham (with eight gilded Buddhas), Wat Khonekeo Xaiyaram (with red, gold, and green doors and pillars), and Wat Keophone Savanthanaram (with

219-635: A 99-year lease for 10,000 hectares on the banks of the Mekong. The company was granted 3,000 of these hectares as a duty-free zone, now the SEZ. As gambling is illegal in China, and the SEZ is only a two-hour journey by road from China, casinos and hotels catering to a Chinese clientele were built. A robust industry involving trafficking in endangered animals has grown up around the Chinese tourist trade. In January 2018,

292-468: A certificate from an independent gemological laboratory attesting to "no evidence of heat treatment". Yogo sapphires do not need heat treating because their cornflower blue color is attractive out of the ground; they are generally free of inclusions , and have high uniform clarity. When Intergem Limited began marketing the Yogo in the 1980s as the world's only guaranteed untreated sapphire, heat treatment

365-399: A dominant red body color. This is generally caused by traces of chromium (Cr ) substituting for the (Al ) ion in the corundum structure. The color can be modified by both iron and trapped hole color centers. Unlike localized ("intra-atomic") absorption of light, which causes color for chromium and vanadium impurities, blue color in sapphires comes from intervalence charge transfer, which is

438-410: A lot of strain due to the high thermal gradient between the flame and surrounding air. To release this strain, the now finger-shaped crystal will be tapped with a chisel to split it into two halves. Due to the vertical layered growth of the crystal and the curved upper growth surface (which starts from a drop), the crystals will display curved growth lines following the top surface of the boule. This

511-400: A rate of 1 to 100 mm per hour. The alumina crystallizes on the end, creating long carrot-shaped boules of large size up to 200 kg in mass. Synthetic sapphire is also produced industrially from agglomerated aluminum oxide, sintered and fused (such as by hot isostatic pressing ) in an inert atmosphere, yielding a transparent but slightly porous polycrystalline product. In 2003,

584-429: A reclining Buddha behind chicken wire) The buildings and barracks of the old French Fort Carnot are now destroyed. Sapphire Sapphire is a precious gemstone , a variety of the mineral corundum , consisting of aluminium oxide ( α- Al 2 O 3 ) with trace amounts of elements such as iron , titanium , cobalt , lead , chromium , vanadium , magnesium , boron , and silicon . The name sapphire

657-503: A respected laboratory such as GIA , Lotus Gemology , or SSEF , is often required by buyers before they will make a purchase. Sapphires in colors other than blue are called "fancy" sapphires. "Parti sapphire" is used for multicolor stones with zoning of different colors (hues), but not different shades. Fancy sapphires are found in yellow, orange, green, brown, purple, violet, and practically any other hue. Gemstone color can be described in terms of hue , saturation , and tone . Hue

730-526: A super-species. It is found in Southeast Asia from north-eastern India to Vietnam. The binomial of this bird commemorates the German naturalist and explorer Otto Finsch . Its face is grey/green, and the rest of its head is dull green with faint pale green band below cheeks to hindcrown and its wing are patch absent and has a long tail. The grey headed parakeet has a wide range in Southeast Asia. It

803-417: A variety of shades. Corundum that contains extremely low levels of chromophores is near colorless. Completely colorless corundum generally does not exist in nature. If trace amounts of iron are present, a very pale yellow to green color may be seen. However, if both titanium and iron impurities are present together, and in the correct valence states, the result is a blue color. Intervalence charge transfer

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876-485: Is a major economic activity. Ban Nam Khok and Ban Houi Sala , about 6 kilometres (3.7 mi) and 18 kilometres (11 mi) from Bokeo town respectively, are notable mining areas. Buhae Industrial Corp., which mines for sapphires , is a major company operating in Houayxay District. Many of the ethnic Lantaen villages are noted for their production of traditional saa paper and other crafts. Paa beuk ,

949-442: Is a process that produces a strong colored appearance at a low percentage of impurity. While at least 1% chromium must be present in corundum before the deep red ruby color is seen, sapphire blue is apparent with the presence of only 0.01% of titanium and iron. Colorless sapphires, which are uncommon in nature, were once used as diamond substitutes in jewelry, and are presently used as accent stones. The most complete description of

1022-459: Is a specific change in energy for the electron, and electromagnetic energy is absorbed. The wavelength of the energy absorbed corresponds to yellow light. When this light is subtracted from incident white light, the complementary color blue results. Sometimes when atomic spacing is different in different directions, there is resulting blue-green dichroism . Purple sapphires contain trace amounts of chromium and iron plus titanium and come in

1095-486: Is a type of sapphire that exhibits a star-like phenomenon known as asterism ; red stones are known as "star rubies". Star sapphires contain intersecting needle-like inclusions following the underlying crystal structure that causes the appearance of a six-rayed "star"-shaped pattern when viewed with a single overhead light source. The inclusion is often the mineral rutile , a mineral composed primarily of titanium dioxide . The stones are cut en cabochon , typically with

1168-439: Is added to the flame, causing it to burn slightly hotter. This expands the growing crystal laterally. At the same time, the pedestal is lowered at the same rate that the crystal grows vertically. The alumina in the flame is slowly deposited, creating a teardrop shaped " boule " of sapphire material. This step is continued until the desired size is reached, the flame is shut off and the crystal cools. The now elongated crystal contains

1241-478: Is an island in Tonpheung District, which is connected to the mainland except during the rainy season. The Bokeo Nature Reserve was created as protection for the black crested gibbon (also known as "black-cheeked gibbon"), discovered in 1997, previously thought to be extinct. Elephants and wild water buffalo migrate through the reserve; bears and tigers are also present. The protected area ,

1314-494: Is called padparadscha . Significant sapphire deposits are found in Australia , Afghanistan , Cambodia , Cameroon , China ( Shandong ), Colombia , Ethiopia , India Jammu and Kashmir ( Padder , Kishtwar ), Kenya , Laos , Madagascar , Malawi , Mozambique , Myanmar ( Burma ), Nigeria , Rwanda , Sri Lanka , Tanzania , Thailand , United States ( Montana ) and Vietnam . Sapphire and rubies are often found in

1387-512: Is characterized by a mixed deciduous forest and mountainous terrain (elevation ranging between 500 and 1500 m). The area covered by the reserve is 136,000 hectares (336,000 acres), including 66,000 hectares (163,000 acres) in Bokeo province and 70,000 hectares (173,000 acres) in Luang Namtha province where critically endangered species of western black crested gibbon ( Nomascus concolor )

1460-451: Is common practice to heat natural sapphires to improve or enhance their appearance. This is done by heating the sapphires in furnaces to temperatures between 800 and 1,800 °C (1,470 and 3,270 °F) for several hours, or even weeks at a time. Different atmospheres may be used. Upon heating, the stone becomes bluer in color, but loses some of the rutile inclusions (silk). When high temperatures (1400 °C+) are used, exsolved rutile silk

1533-428: Is commonly understood as the " color " of the gemstone. Saturation refers to the vividness or brightness of the hue, and tone is the lightness to darkness of the hue. Blue sapphire exists in various mixtures of its primary (blue) and secondary hues, various tonal levels (shades) and at various levels of saturation (vividness). Blue sapphires are evaluated based upon the purity of their blue hue. Violet and green are

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1606-556: Is derived from the Latin word sapphirus , itself from the Greek word sappheiros ( σάπφειρος ), which referred to lapis lazuli . It is typically blue, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colors; "parti sapphires" show two or more colors. Red corundum stones also occur, but are called rubies rather than sapphires. Pink-colored corundum may be classified either as ruby or sapphire depending on

1679-409: Is dissolved and it becomes clear under magnification. The titanium from the rutile enters solid solution and thus creates with iron the blue color. The inclusions in natural stones are easily seen with a jeweler's loupe . Evidence of sapphire and other gemstones being subjected to heating goes back at least to Roman times. Un-heated natural stones are somewhat rare and will often be sold accompanied by

1752-416: Is found in elevations of up to 2,700 meters in forests consisting of oak , teak , pine , and cedar trees . It also resides on deciduous forest hillsides, farmland with scattered trees. In Cambodia, it regularly occurs in areas with evergreen and semi-evergreen vegetation. The grey headed parakeet has a widely varied diet of different species of leaf buds, seeds , fruit , berries , and flowers . It

1825-476: Is found in most of Vietnam, the entire country of Laos, most of eastern Cambodia, northern Thailand, in most of Myanmar (except for Tanintharyi Region ), in the Yunnan province of China, in far east Bangladesh (extremely rare), nearly all of Northeast India , and far southeast Bhutan. The global population size is not known, but this bird is reported to be uncommon in China, with varying statuses everywhere else. It

1898-557: Is heavily tilted to the red end of the spectrum, thus tipping the balance to red. Color-change sapphires colored by the Cr + Fe/Ti chromophores generally change from blue or violet-blue to violet or purple. Those colored by the V chromophore can show a more pronounced change, moving from blue-green to purple. Certain synthetic color-change sapphires have a similar color change to the natural gemstone alexandrite and they are sometimes marketed as "alexandrium" or "synthetic alexandrite". However,

1971-432: Is in contrast to natural corundum crystals, which feature angular growth lines expanding from a single point and following the planar crystal faces. Chemical dopants can be added to create artificial versions of the ruby, and all the other natural colors of sapphire, and in addition, other colors never seen in geological samples. Artificial sapphire material is identical to natural sapphire, except it can be made without

2044-574: Is often seen in flocks or family parties, with larger groups reported. It is usually a resident bird, with some seasonal altitudinal movement in response to food availability. It often gathers in large flocks to roost at dusk. After their breeding season from January–March, females often lay a clutch of 4-5 eggs that are around 28.5 x 22.0mm. The grey-headed parakeet is often captured in the exotic bird trade and many are locally kept as pets. They tend to be popular in some small villages in southern China and surrounding areas. The constant trapping of birds

2117-416: Is required of any mode of enhancement that has a significant effect on the gem's value. There are several ways of treating sapphire. Heat-treatment in a reducing or oxidizing atmosphere (but without the use of any other added impurities) is commonly used to improve the color of sapphires, and this process is sometimes known as "heating only" in the gem trade. In contrast, however, heat treatment combined with

2190-460: Is the primary protected species. According to a preliminary survey, the number of gibbons is substantial, particularly in and around the uninhabited Nam Kan River and its tributaries. The project is being supported by the French entrepreneur Jean Francois Reumaux as a Gibbon Experience Project. Gibbon Experience is a conservation project that came into existence after the indigenous black-cheeked gibbon

2263-709: Is thought to be the third-largest star sapphire, and is currently on display at the American Museum of Natural History in New York City . The 182-carat Star of Bombay , mined in Sri Lanka and located in the National Museum of Natural History in Washington, D.C. , is another example of a large blue star sapphire. The value of a star sapphire depends not only on the weight of the stone, but also

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2336-633: The Star of India , The Star of Adam and the Star of Bombay originate from Sri Lankan mines. Madagascar is the world leader in sapphire production (as of 2007) specifically its deposits in and around the town of Ilakaka . Prior to the opening of the Ilakaka mines, Australia was the largest producer of sapphires (such as in 1987). In 1991 a new source of sapphires was discovered in Andranondambo, southern Madagascar. The exploitation started in 1993, but

2409-537: The US Treasury Department announced sanctions against what it called Zhao's transnational criminal organisation, engaging in illicit activities, including human trafficking and child prostitution, drug trafficking and wildlife trafficking. Houayxay, the capital city of the province, has most of the remainder of the province's economic activity. The province is one of the main maize producing areas of Laos. Commercial mining for precious stones and gold

2482-566: The chromium chromophore that creates the red color of ruby, combined with the iron + titanium chromophore that produces the blue color in sapphire. A rarer type, which comes from the Mogok area of Myanmar, features a vanadium chromophore, the same as is present in Verneuil synthetic color-change sapphire. Virtually all gemstones that show the "alexandrite effect" (color change or ' metamerism ') show similar absorption/transmission features in

2555-545: The insulating substrates of special-purpose solid-state electronics such as integrated circuits and GaN -based blue LEDs . Sapphire is the birthstone for September and the gem of the 45th anniversary . A sapphire jubilee occurs after 65 years. Sapphire is one of the two gem-varieties of corundum , the other being ruby (defined as corundum in a shade of red). Although blue is the best-known sapphire color, it occurs in other colors, including gray and black, and also can be colorless. A pinkish orange variety of sapphire

2628-665: The 12.00 carat Cartier sapphire ring at US$ 193,975 per carat, then with a 17.16 carat sapphire at US$ 236,404, and again in June 2015 when the per-carat auction record was set at US$ 240,205. At present, the world record price-per-carat for sapphire at auction is held by a sapphire from Kashmir in a ring, which sold in October 2015 for approximately US$ 242,000 per carat ( HK$ 52,280,000 in total, including buyer's premium, or more than US$ 6.74 million). Sapphires can be treated by several methods to enhance and improve their clarity and color. It

2701-471: The French chemist Auguste Verneuil announced a process for producing synthetic ruby crystals. In the flame-fusion ( Verneuil process ), fine alumina powder is added to an oxyhydrogen flame , and this is directed downward against a ceramic pedestal. Following the successful synthesis of ruby, Verneuil focused his efforts on sapphire. Synthesis of blue sapphire came in 1909, after chemical analyses of sapphire suggested to Verneuil that iron and titanium were

2774-568: The Lanten, Hmong, Lahu, Yao, Akha, and Tai Lue peoples. The Lahu, a Tibeto-Burman speaking people who are part of ethnic group of northern Myanmar and Thailand also inhabit this province in large numbers. The provincial economy is now dominated by the Golden Triangle Special Economic Zone (GT SEZ). In 2007, Kings Romans Group, owned by well-connected Chinese husband and wife Zhao Wei and Su Guiqin, entered into

2847-547: The Nam Nga River. Other than gibbons, wildlife in the reserve reported are: great barbet ( Megalaima virens ); grey-headed parakeet ( Psittacula finschii ); grey leaf monkeys ( Semnopithecus ); crab-eating mongoose ( Herpestes urva ), tiger ( Panthera tigris ); smaller cats; dhole ( Cuon alpinus ), bears (two types); otters ; sambar ( Cervus unicolor ); and wild cattle ( gaur ). The 10,980 hectare Upper Lao Mekong Important Bird Area (IBA) stretches across

2920-698: The area of Franklin, North Carolina . The sapphire deposits of Kashmir are well known in the gem industry, although their peak production took place in a relatively short period at the end of the nineteenth and early twentieth centuries. These deposits are located in the Paddar Valley of the Jammu region of Jammu and Kashmir in India. They have a superior vivid blue hue, coupled with a mysterious and almost sleepy quality, described by some gem enthusiasts as ‘blue velvet”. Kashmir-origin contributes meaningfully to

2993-591: The biggest problem the Yogo mine faced was not competition from heated sapphires, but the fact that the Yogo stones could never produce quantities of sapphire above one carat after faceting. As a result, it has remained a niche product, with a market that largely exists in the US. Lattice ('bulk') diffusion treatments are used to add impurities to the sapphire to enhance color. This process was originally developed and patented by Linde Air division of Union Carbide and involved diffusing titanium into synthetic sapphire to even out

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3066-415: The blue color. It was later applied to natural sapphire. Today, titanium diffusion often uses a synthetic colorless sapphire base. The color layer created by titanium diffusion is extremely thin (less than 0.5 mm). Thus repolishing can and does produce slight to significant loss of color. Chromium diffusion has been attempted, but was abandoned due to the slow diffusion rates of chromium in corundum. In

3139-466: The body color, visibility, and intensity of the asterism. The color of the stone has more impact on the value than the visibility of the star. Since more transparent stones tend to have better colors, the most expensive star stones are semi-transparent "glass body" stones with vivid colors. On 28 July 2021, the world's largest cluster of star sapphires, weighing 510 kg (1,120 lb), was unearthed from Ratnapura, Sri Lanka. This star sapphire cluster

3212-433: The cause of the blue color. Verneuil patented the process of producing synthetic blue sapphire in 1911. The key to the process is that the alumina powder does not melt as it falls through the flame. Instead it forms a sinter cone on the pedestal. When the tip of that cone reaches the hottest part of the flame, the tip melts. Thus the crystal growth is started from a tiny point, ensuring minimal strain. Next, more oxygen

3285-1278: The causes of color in corundum extant can be found in Chapter ;4 of Ruby & Sapphire: A Gemologist's Guide (chapter authored by John Emmett, Emily Dubinsky and Richard Hughes). Sapphires are mined from alluvial deposits or from primary underground workings. Commercial mining locations for sapphire and ruby include (but are not limited to) the following countries: Afghanistan , Australia , Myanmar / Burma , Cambodia , China , Colombia , India , Kenya , Laos , Madagascar , Malawi , Nepal , Nigeria , Pakistan , Sri Lanka , Tajikistan , Tanzania , Thailand , United States, and Vietnam . Sapphires from different geographic locations may have different appearances or chemical-impurity concentrations, and tend to contain different types of microscopic inclusions. Because of this, sapphires can be divided into three broad categories: classic metamorphic, non-classic metamorphic or magmatic, and classic magmatic. Sapphires from certain locations, or of certain categories, may be more commercially appealing than others, particularly classic metamorphic sapphires from Kashmir, Burma, or Sri Lanka that have not been subjected to heat-treatment. The Logan sapphire ,

3358-459: The center of the star near the top of the dome. Occasionally, twelve-rayed stars are found, typically because two different sets of inclusions are found within the same stone, such as a combination of fine needles of rutile with small platelets of hematite ; the first results in a whitish star and the second results in a golden-colored star. During crystallization, the two types of inclusions become preferentially oriented in different directions within

3431-409: The color penetration is far greater than with titanium diffusion. In some cases, it may penetrate the entire stone. Beryllium-diffused orange sapphires may be difficult to detect, requiring advanced chemical analysis by gemological labs ( e.g. , Gübelin, SSEF , GIA , American Gemological Laboratories (AGL), Lotus Gemology . According to United States Federal Trade Commission guidelines, disclosure

3504-470: The crystal, thereby forming two six-rayed stars that are superimposed upon each other to form a twelve-rayed star. Misshapen stars or 12-rayed stars may also form as a result of twinning . The inclusions can alternatively produce a cat's eye effect if the girdle plane of the cabochon is oriented parallel to the crystal's c-axis rather than perpendicular to it. To get a cat's eye, the planes of exsolved inclusions must be extremely uniform and tightly packed. If

3577-690: The deliberate addition of certain specific impurities (e.g. beryllium, titanium, iron, chromium or nickel, which are absorbed into the crystal structure of the sapphire) is also commonly performed, and this process can be known as "diffusion" in the gem trade. However, despite what the terms "heating only" and "diffusion" might suggest, both of these categories of treatment actually involve diffusion processes. The most complete description of corundum treatments extant can be found in Chapter 6 of Ruby & Sapphire: A Gemologist's Guide (chapter authored by John Emmett, Richard Hughes and Troy R. Douthit). In 1902,

3650-448: The dome is oriented in between these two directions, an off-center star will be visible, offset away from the high point of the dome. At 1404.49 carats, The Star of Adam is the largest known blue star sapphire. The gem was mined in the city of Ratnapura, southern Sri Lanka. The Black Star of Queensland , the second largest star sapphire in the world, weighs 733 carats . The Star of India mined in Sri Lanka and weighing 563.4 carats

3723-543: The flaws that are found in natural stones. The disadvantage of the Verneuil process is that the grown crystals have high internal strains. Many methods of manufacturing sapphire today are variations of the Czochralski process , which was invented in 1916 by Polish chemist Jan Czochralski . In this process, a tiny sapphire seed crystal is dipped into a crucible made of the precious metal iridium or molybdenum , containing molten alumina, and then slowly withdrawn upward at

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3796-446: The following districts: Its population was 179,243 in 2015, in 36 townships, and more than 400 villages. With 34 ethnic groups (including Akha, Hmong, Khamu, Kalom, Kui, Lamet, Lao Huay, Mien, Musoe, Ngo, Phai, Phu Thai, Phuan, Phuvan, Samtao, Shan, Tahoy, Thai Daeng, Thai Dam, Thai Khao, Thai Lu, Thai Nai, and Chinese), the province's ethnic diversity is ranked second in the country, after Luang Namtha province . Most numerous though are

3869-436: The highest premium, although Burma, Sri Lanka, and Madagascar also produce large quantities of fine quality gems. The cost of natural sapphires varies depending on their color, clarity, size, cut , and overall quality. Sapphires that are completely untreated are worth far more than those that have been treated. Geographical origin also has a major impact on price. For most gems of one carat or more, an independent report from

3942-666: The largest faceted gem-quality blue sapphires in existence. Particolored sapphires (or bi-color sapphires) are those stones that exhibit two or more colors within a single stone. The desirability of particolored or bi-color sapphires is usually judged based on the zoning or location of their colors, the colors' saturation, and the contrast of their colors. Australia is the largest source of particolored sapphires; they are not commonly used in mainstream jewelry and remain relatively unknown. Particolored sapphires cannot be created synthetically and only occur naturally. Pink sapphires occur in shades from light to dark pink, and deepen in color as

4015-411: The latter term is a misnomer: synthetic color-change sapphires are, technically, not synthetic alexandrites but rather alexandrite simulants . This is because genuine alexandrite is a variety of chrysoberyl : not sapphire, but an entirely different mineral from corundum. Large rubies and sapphires of poor transparency are frequently used with suspect appraisals that vastly overstate their value. This

4088-679: The locale. Commonly, natural sapphires are cut and polished into gemstones and worn in jewelry . They also may be created synthetically in laboratories for industrial or decorative purposes in large crystal boules . Because of the remarkable hardness of sapphires – 9 on the Mohs scale (the third-hardest mineral, after diamond at 10 and moissanite at 9.5) – sapphires are also used in some non-ornamental applications, such as infrared optical components, high-durability windows , wristwatch crystals and movement bearings, and very thin electronic wafers , which are used as

4161-406: The most common secondary hues found in blue sapphires. The highest prices are paid for gems that are pure blue and of vivid saturation. Gems that are of lower saturation, or are too dark or too light in tone are of less value. However, color preferences are a personal taste. The 423-carat (84.6 g) Logan sapphire in the National Museum of Natural History , in Washington, D.C. , is one of

4234-420: The past, Houayxay town was a marked crossroad trading centre between Yunnan province of China and Thailand, particularly for Chinese goods. Bokeo province is the smallest of the country's provinces, covering an area of 6,196 square kilometres (2,392 sq mi). Bokeo province borders Luang Namtha province to the northeast, Oudomxay province to the east, Sainyabuli province to the south, Thailand to

4307-644: The provinces of Bokeo, Oudomxay, and Sainyabuli. It is at an elevation of 300–400 metres (980–1,310 ft). The topography features river channels, exposed beds, sandbars, sand and gravel bars, islands, rock outcrops, bushland, and braided streams. Confirmed avifauna include black-bellied tern ( Sterna acuticauda ), great cormorant ( Phalacrocorax carbo ), grey-headed lapwing ( Vanellus cinereus ), Jerdon's bush chat ( Saxicola jerdoni ), brown-throated martin ( Riparia paludicola ), river lapwing ( Vanellus duvaucelii ), small pratincole ( Glareola lactea ), and swan goose ( Anser cygnoides ). The province includes

4380-648: The quantity of chromium increases. The deeper the pink color, the higher their monetary value . In the United States, a minimum color saturation must be met to be called a ruby , otherwise the stone is referred to as a pink sapphire . Padparadscha is a delicate, light to medium toned, pink-orange to orange-pink hued corundum , originally found in Sri Lanka , but also found in deposits in Vietnam and parts of East Africa . Padparadscha sapphires are rare;

4453-522: The rarest of all is the totally natural variety, with no sign of artificial treatment. The name is derived from the Sanskrit padma ranga (padma = lotus; ranga = color), a color akin to the lotus flower ( Nelumbo nucifera ). Among the fancy (non-blue) sapphires, natural padparadscha fetch the highest prices. Since 2001, more sapphires of this color have appeared on the market as a result of artificial lattice diffusion of beryllium. A star sapphire

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4526-463: The same geographical settings, but they generally have different geological formations. For example, both ruby and sapphire are found in Myanmar's Mogok Stone Tract, but the rubies form in marble, while the sapphire forms in granitic pegmatites or corundum syenites. Every sapphire mine produces a wide range of quality, and origin is not a guarantee of quality. For sapphire, Jammu and Kashmir receives

4599-412: The southwest, and Burma to the west and northwest. Notable settlements include Houayxay , Mong Lin , Ban Thakate , Ban Meung Hong , Ban Ha Li Tai , Ban Khai San , Ban Nam Kueng , Ban Long and Ban Paung . The Nam Nga River flows through the province's Bokeo Nature Reserve , and is hemmed between the Mekong River bordering Thailand and Burma and is also on the trade route with China . Don Sao

4672-412: The transfer of an electron from one transition-metal ion to another via the conduction or valence band . The iron can take the form Fe or Fe , while titanium generally takes the form Ti . If Fe and Ti ions are substituted for Al , localized areas of charge imbalance are created. An electron transfer from Fe and Ti can cause a change in the valence state of both. Because of the valence change, there

4745-506: The value of a sapphire, and most corundum of Kashmir origin can be readily identified by its characteristic silky appearance and exceptional hue. The unique blue appears lustrous under any kind of light, unlike non-Kashmir sapphires which may appear purplish or grayish in comparison. Sotheby's has been in the forefront overseeing record-breaking sales of Kashmir sapphires worldwide. In October 2014, Sotheby's Hong Kong achieved consecutive per-carat price records for Kashmir sapphires – first with

4818-445: The visible spectrum. This is an absorption band in the yellow (~590 nm), along with valleys of transmission in the blue-green and red. Thus the color one sees depends on the spectral composition of the light source. Daylight is relatively balanced in its spectral power distribution (SPD) and since the human eye is most sensitive to green light, the balance is tipped to the green side. However incandescent light (including candle light)

4891-407: The world's production of synthetic sapphire was 250 tons (1.25 × 10 carats), mostly by the United States and Russia. The availability of cheap synthetic sapphire unlocked many industrial uses for this unique material. Grey-headed parakeet Himalayapsitta finschii The grey-headed parakeet ( Psittacula finschii ) is closely related to the slaty-headed parakeet which together form

4964-416: The year 2000, beryllium diffused "padparadscha" colored sapphires entered the market. Typically beryllium is diffused into a sapphire under very high heat, just below the melting point of the sapphire. Initially ( c.  2000 ) orange sapphires were created, although now the process has been advanced and many colors of sapphire are often treated with beryllium. Due to the small size of the beryllium ion,

5037-401: Was discovered. The conservation programme has two components: one is of gibbon viewing huts, known as canopy huts (there are four such very large huts) in the forest reserve meant to view the black cheeked gibbons and the second component is to experience the rain forest at canopy level. The Waterfall Gibbon Experience involves three hours of hiking to the location, deep in the reserve following

5110-490: Was named " Serendipity Sapphire ". A rare variety of natural sapphire, known as color-change sapphire, exhibits different colors in different light. Color change sapphires are blue in outdoor light and purple under incandescent indoor light, or green to gray-green in daylight and pink to reddish-violet in incandescent light. Color-change sapphires come from a variety of locations, including Madagascar , Myanmar , Sri Lanka and Tanzania . Two types exist. The first features

5183-550: Was not commonly disclosed; by the late 1980s, heat treatment became a major issue. At that time, much of all the world's sapphires were being heated to enhance their natural color. Intergem's marketing of guaranteed untreated Yogos set them against many in the gem industry. This issue appeared as a front-page story in The Wall Street Journal on 29 August 1984 in an article by Bill Richards, Carats and Schticks: Sapphire Marketer Upsets The Gem Industry . However,

5256-613: Was practically abandoned just a few years later because of the difficulties in recovering sapphires in their bedrock. In North America , sapphires have been mined mostly from deposits in Montana : facies along the Missouri River near Helena, Montana , Dry Cottonwood Creek near Deer Lodge, Montana , and Rock Creek near Philipsburg, Montana . Fine blue Yogo sapphires are found at Yogo Gulch west of Lewistown, Montana . A few gem-grade sapphires and rubies have also been found in

5329-672: Was the case of the "Life and Pride of America Star Sapphire". Circa 1985, Roy Whetstine claimed to have bought the 1905-ct stone for $ 10 at the Tucson gem show, but a reporter discovered that L.A. Ward of Fallbrook, California, who appraised it at the price of $ 1200/ct, had appraised another stone of the exact same weight several years before Whetstine claimed to have found it. Bangkok-based Lotus Gemology maintains an updated listing of world auction records of ruby, sapphire, and spinel . As of November 2019, no sapphire has ever sold at auction for more than $ 17,295,796. Rubies are corundum with

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