Stones by zodiac signs

What is the difference between corundum and sapphire?

In ancient times, a variety of blue stones were called sapphires – from sapphire to lapis lazuli. At the beginning of the 19th century. it turned out that sapphire and ruby ​​represent are jewelry varieties of corundum. At first, only the blue variety was called sapphire; transparent corundums of colors other than red were given special, purely trade names: for example, green corundum was called oriental peridot or oriental emerald, yellow corundum was called oriental topaz, etc. These kinds of names were often misleading. Today, the name “sapphire” refers to jewelry corundums of any color except red – ruby. It is now customary to indicate the color of sapphire specifically. For example: green or yellow sapphire. If it says simply “sapphire”, we are talking only about a blue stone. Colorless sapphire is also called leucosapphire, orange-yellow is called padparadscha in Sinhalese – “lotus flower”). There is no sharp boundary between sapphires of pinkish-violet tones and ruby. Light red, pink and purple corundums are usually classified as sapphires: after all, among sapphires they are rated quite highly, but as rubies they would be considered low-grade. The chromophore in blue sapphire is iron and titanium, and in violet sapphire it is vanadium. A slight admixture of ferric iron gives the sapphire a yellow color, and divalent iron gives it a green color. The pink tints are due to an admixture of chromium. The most prized are cornflower blue sapphires of pure water. The hardness of sapphire is as high as that of ruby, and depends to the same extent on the direction in the crystal. It is important to take into account the anisotropy of hardness when cutting. There is no single luminescence color characteristic of all sapphires – its color depends on the stone’s own color and on the deposit. Inclusions of rutile needles cause the silky shine of the stone, in large quantities – the effect of a “cat’s eye” and a six-rayed star: star sapphire. According to some researchers, the asterism of sapphire, unlike ruby, is caused not by rutile needles, but by hollow channels oriented in three directions. The host rocks of sapphire deposits are marbles or basalts. They are also formed in pegmatites, but are mined mainly from alluvial placers or weathering crusts, less often from bedrock. Development methods are extremely simple: manually driven pits or pits and eroded slopes allow the development of sapphire-bearing formations located at depth. Clay, sand and gravel are separated by washing; Sapphires accumulate due to their high density. Finally, the sapphires are manually selected and classified according to quality. Sapphire is much more widespread than its closest relative, ruby, since the chromophore of sapphires is iron, and not the rare chromium that colors rubies. Place of Birth Industrially significant sapphire deposits are now located in Australia, Burma, Sri Lanka and Thailand.
Australian deposits in Queensland have been known since 1870. The host rocks there are basalts, from the weathered upper layer of which sapphires are extracted by washing. Their quality is low. The deep blue color of these stones becomes inky, greenish or even almost black in artificial light. Lighter stones also have a green tint. Black star sapphires have recently been discovered. Associated minerals of Australian sapphires are quartz, pyrope, topaz, tourmaline, and zircon. In 1918, good quality blue sapphires were discovered in New South Wales. Subsequently, these deposits apparently became very productive. In Upper Burma, near Mogok, alluvial placers are mined, containing, along with sapphire, also ruby ​​and spinel. Their parent rocks are pegmatites. In 1966, the largest star sapphire was found here – a crystal weighing 63 carats (000 kg!). On the island of Sri Lanka, sapphires have been mined since ancient times. The deposits there are located in the southwestern part of the island, in the Ratnapura region. The host rocks are remnants of dolomitized limestones in granites or their interlayers in gneisses. Placers of river pebbles with a thickness of 30-60 cm (in the local dialect “illam”), located at a depth of 2 to 10 m, are being mined. The sapphires in them are mainly light blue, often with a violet tint. In addition, there are also yellow and orange varieties of the Padparadscha type and, along with them, green, pink, brown and almost colorless stones, and finally, star sapphires and cat’s eye sapphires. Associated minerals are very numerous: apatite, garnet, quartz, cordierite, topaz, tourmaline, zircon, spinel, epidote. There are two sapphire deposits in Thailand: one (Bang Kha Cha) is located near Chanthaburi, 220 km southeast of Bangkok, the other (Bo Phloy) is near Kanchanaburi, 120 km northwest of Bangkok. The host rocks are marbles or basalts. Deposits confined to placers and weathering crusts are being developed. Satellite minerals: garnet, ruby, zircon, spinel. The sapphires here are of good quality and come in a variety of colors, including star-shaped ones. The stones are a deep blue color, however, usually with a greenish tint. Kashmir sapphires (India) are more prized than others. The deposits there are located at an altitude of 5000 m (Zanskar Range in the Himalayas) 200 km southeast of Srinagar. They have been in use with varying success since 1880 and are now abandoned. Sapphires there were mined from a highly kaolinized pegmatite vein embedded in crystalline marbles. From the grit of these pegmatites, sapphires of thick cornflower blue, often with a silky tint, were extracted. Burmese sapphires are often passed off as Kashmiri. In 1894, sapphire deposits were discovered in the state. Montana (USA), confined to an andesite dike. Stones were extracted both from the dike itself and from the crushed stone formed during its weathering. The colors of Montana sapphires are very varied, often being pale blue or steel blue. Development of the field was stopped in the late 20s of the XNUMXth century. Currently, work has been resumed here at Iogo-Talch.
Sapphire deposits are also known in Brazil (Mato Grosso), in the west of Kampuchea, in Kenya, Malawi, Zimbabwe and, more recently, in the north of Tanzania. Single finds of star sapphires occur in the north of Finland (in Lapland). Manifestations of blue sapphire in the territory of the former USSR, associated with syenite pegmatites of the Ilmen Mountains in the Urals and with napheline-syenite pegmatites of the Khibiny massif on the Kola Peninsula, are small and, in addition, can serve as sources for obtaining low-quality cutting raw materials, suitable only for the production of small stones “spark” type. Large sapphires are rare. Sometimes, like famous diamonds, they are given their own names. The American Museum of Natural History (New York) owns the Star of India, probably the largest cut star sapphire (536 ct), as well as the black Midnight Star sapphire (116 ct). The Smithsonian Institution (Washington) acquired the Star of Asia star sapphire (330 ct). Two famous sapphires (St. Edward’s and Stuart’s) are among the British Crown Jewels. In the USA, sculptural portraits of US presidents: Washington, Lincoln and Eisenhower are carved from three sapphires, weighing approximately 2000 carats each. The collection of the Diamond Fund of Russia has blue Ceylon sapphires that are unique in beauty and weight; one of them (200 karat) is mounted in the cross of the Russian Empire, the other (258 karat) is inserted into a brooch. Deposits of corundum (ruby and sapphire)

Brazil (Jauro, Matto Grosso): dark blue sapphire
Burma: ruby (excellent quality)
sapphire blue
Thailand: ruby
dark red ruby
sapphire blue, yellow, green
Kashmir: cornflower blue sapphire
Pakistan: ruby
Tanzania (Hunza Valley): orange sapphire
Australia: sapphire blue, yellow, green
Malawi: sapphires of different colors
ruby
Slovenia (Prilip): ruby

Fake sapphires Many stones are similar to blue sapphire: benitoite, kyanite, cordierite, tanzanite, topaz, tourmaline, zircon starlite, spinel; They also imitate it with blue glass. There are many trade names that mislead the buyer: for example, Brazilian sapphire is called blue topaz, oriental sapphire is called blue tourmaline.
Doublets “look like sapphire” are made of blue cobalt glass and a thin garnet overlay on the stone platform, or the upper part is made of greenish sapphire, and the lower part is made of synthetic blue sapphire. Recently, doublets made up of two small natural sapphires have appeared. Star sapphires are imitated using star rose quartz; The flat lower part of the stone is covered with blue enamel. In another imitation method, a star is engraved on the smooth underside of a synthetic sapphire or glass cabochon.
At the beginning of the century, they learned to grow synthetic sapphires, whose properties are very close to natural ones. Since 1947, synthetic star sapphires of gem quality have also been produced. The article used materials from:
1. V. Schumann. World of stone. Precious and ornamental stones, M.: -1986.
2. Ya.P. Samsonov, A.P. Touring. Gems of the USSR, M., Nedra – 1984.
3. Joel E.Arem.PhD. FG AColor encyclopedia of gemstones -1977

Ruby or sapphire: how to distinguish what they have in common and why rubies and sapphires in the USSR were fake

Have you ever seen a green sapphire? What about yellow? It’s a paradox, but this happens in reality and the phenomenon itself is ordinary. Clear associations between the names of stones and color schemes have already formed in the human mind, but the facts are often surprising. It will be so this time in a new interview, which we prepared especially for visitors to the Stones Market online store and all those interested. Let’s meet again today to talk about some issues of minerals and stones. Today we are in the studio with a well-known specialist in Ukraine again, geologist Andrei Ivanovich Martishin, and we invited him to help us understand this issue. Andrey Ivanovich, there are sapphires, there are rubies, and very often we see that these two names go side by side, even sapphire-ruby, or ruby-sapphire. Could you please explain why this is so, what it means. – The minerals ruby ​​and sapphire do not exist in nature; there is a mineral called corundum. It has a banally simple chemical formula – aluminum oxide Al2O3, it crystallizes, the crystals most often have the form of hexagonal columns, so to speak (top left – approx.), to hexagonal tablets (bottom left – approx.). It comes in various colors, here we have blue – this is actually sapphire (top left – approx.), various shades of red and pink – this is called ruby ​​(top right – approx.), and everything, absolutely everything, of any colors – green, orange, everything that is not red is called sapphire. Therefore, those who think that sapphire comes only in blue are mistaken; it comes in any color except red. This entire group of corundum is formed mainly under conditions of so-called regional metamorphism. Simply put, marine sediments that had a lot of clay with them, when they sink deep into the earth and under high pressure and rising temperatures, begin to recrystallize, and aluminum, due to molecular forces of attraction, forms such crystals, depending on the impurities they will have different colors. Therefore, they will be called either ruby ​​or sapphire. There are cases when different solutions are impulsively received in different sequences, so they can be polychrome, for example, a blue sapphire can turn into a pink sapphire, and then into a red ruby. There are such crystals, they are found most often in India in Kashmir; probably everyone has heard about the deposit of Indian rubies and sapphires. – Is that when they say that it is sapphire-ruby or ruby-sapphire? – Well, the question is, let’s say, controversial, since there are no clear criteria for where a sapphire ends and where a ruby ​​begins. Moreover, each person perceives the color scheme differently, so everyone decides for themselves – is this already a ruby, or is this still a sapphire. But in general terms: everything that is red or pink is a ruby, everything else is a sapphire. – Regarding a simple check on whether it is a sapphire or a ruby, you said before the broadcast that this can be done using a fluorescent flashlight. Can we demonstrate this now? Yes, of course, turn off the lights. (It became dark) (turned on the flashlight) (red stones glow) As you can see, the amazing glow effect of these rubies at the very bottom (bottom right – approx.), These are Indian, then the rubies from Tanzania glow less (top right – approx.), and the sapphires almost do not glow. For illustration, we used this sample (top right – note), this is Tanzania, this sapphire from Madagascar (top left – note), these are also colorless Madagascar leucosapphires, and a very interesting deposit from India, which were very luminous (bottom right – approx.), this is a mass of crystals in the oxide-albite rock, unfortunately, they are fractured, but sometimes there are jewelry rubies there. – That is, such a small discovery for myself: there are no sapphires and no rubies, but there is corundum. – These are actually jewelry names; there are no such minerals. There is a very important point that I constantly encounter at exhibitions and when giving consultations, please do not be offended by me, we are all citizens of the former USSR, everyone who bought jewelry with rubies, sapphires and alexandrites in Soviet jewelry stores, all this is a deception of citizens, because all this is aluminum oxide with various impurities, grown in Soviet factories, mainly in the city of Alexandrov near Moscow, which were sold to Soviet citizens at the price of gold, so the state deceived its citizens. – Thank you, Andrey! We hope that now you will become better oriented in matters of gemology. And the main thing is to understand the versatility of sapphires, to know about the common base with rubies, to be able to distinguish rubies from different parts of the world. Let us immediately note that you can choose a stone that suits your liking and wallet directly on our website using these links: sapphires and rubies. As you can see, the catalog presents not only raw stones, but also finished products, including precious jewelry. If you need help with the selection of stones, then contact us in a way convenient for you. We will give you advice, answer questions and help you decide on the mineral directly for you or your loved ones. The Stones Market online store always offers high-quality and natural products at reasonable prices.

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