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Corundum, ruby ​​and sapphire

Corundum, ruby ​​and sapphire

Looking at transparent corundum, fiery red ruby ​​and blue sapphire, few of us can assume that these, so different in appearance, stones have something in common. Meanwhile, all the above-mentioned minerals are very similar in their physicochemical properties.

In essence, they differ only in the presence of various impurities, thanks to which the stones acquire one or another color. Pure corundum is colorless, chromium oxide gives the stone all shades of red, titanium is able to color the mineral blue, and iron oxide gives crystals a yellow tint.

However, in ancient times, when it was not possible to conduct a deep analysis of the composition of minerals, the classification of stones was carried out according to the principle of external similarity. For example, the word "corundum" was used to describe the extremely hard stones, second only to diamond, imported from India.

Sapphires (from the Greek "sappheiros", which in turn comes from the Hebrew "sappir" - "blue") was most often called lapis lazuli and other blue opaque minerals. The word "ruby" (from the Latin "rubens" - "red") appeared only 300 years BC. Before that, all red, glowing stones (red garnets, rubies, spinel) were called carbuncles in the countries of medieval Europe and yachons in Russia.

It was the ruby, sparkling in the dark like a red-hot ember, that was valued in ancient times higher than diamond. In the Roman Empire, this stone was dedicated to the god of war Ares and the titan Kronos, in India, China, Burma, Japan, it was considered a symbol of vitality, love, passion, as well as royal dignity.

The sailors always took it with them on a voyage, as it was believed that this stone is capable of preventing shipwrecks. In India, rubies called "ratnaraj" (translated from Sanskrit - "king of precious stones"), or "ratnanayaka" ("leader of precious stones") were divided into four castes (like the whole society).

In accordance with belonging to one caste or another, the stone had a different effect on the person who possessed it. The ruby ​​brahmana contributed to the awakening of spiritual energy, the kshatriya helped to gain power over people, bestowed invincibility in battle, the vaisya could ensure good luck in trade, and the sudra was only suitable for making jewelry.

The magicians of Burma believed that a ruby ​​sewn under the skin would make a person completely invulnerable to arrows, swords, spears and bullets. In addition, it was believed that the color change of this stone can alert the owner of the danger. At the same time, in order to best manifest the magical properties of the crystal, it should be worn as a pendant at the level of the heart, and so that the stone is in constant contact with the body.

What is it really, this mysterious stone, so diverse in color and magical properties attributed to it? We will try to find the answer to this question, while making efforts to debunk the most persistent myths and misconceptions about corundum and its varieties.

Ruby and sapphire have nothing in common. In fact, both of these stones are a kind of corundum - a mineral second only to diamond in hardness, and rightfully, along with diamond, emerald and pearl, firmly holding the leading position in the world of jewelry.

Sapphire can only be blue. Jewelers use the word "sapphire" for all varieties of corundum, with the exception of red ruby. Sapphire can be white, yellow, green, pink, black. The word padmaradshah or padmaradsha (from the Sinhalese padmaragaya - lotus color) is used to denote the pink-red with a yellowish tinge of the precious material mined in Ceylon.
In ancient times, colored varieties of corundum (now most often referred to as sapphires) were called differently. For example, yellow stones were called "oriental topaz", yellowish-green - "oriental chrysolites", green - "oriental emeralds", bluish-green - "oriental aquamarines", purple - "oriental amethysts", pink - "oriental hyacinths".

Corundum is used only for making jewelry. Completely erroneous opinion. Opaque stones, ground into powder and used as an abrasive, are referred to in the trade as "corundum". In addition, the well-known "emery" also represents corundum crushed into powder, mixed with magnetite and other heavy minerals. "Diamond spar" - crushed dull corundum from India - is used for grinding. In addition, bearings for moving parts in high-precision instruments and watches are made from corundum. But in this area, synthetic stones are most often used. And finally, since 1960, a ruby ​​laser has been used in various industries (from medicine to space research), the beams of which can easily burn through sheet material, drill a hole in hard alloys, etc.

The color of corundum is uniform. This is often not the case. On closer inspection, you will notice that, for example, lilac stones are composed of alternating blue and red layers. Yellow-blue spotted stones are often found, and some asteria (star-shaped stones), due to the peculiarities of the crystal structure, cut in the form of cabochons, under appropriate lighting, give a bright light six-rayed star. The most commonly found blue (star sapphire) and red (star ruby) stones of this kind.

Sapphire is a blue variety of corundum. Indeed, this term is most often used in this sense. But sometimes it can be applied to other minerals. For example, blue tourmaline is sometimes called "Brazilian sapphire", and cordierite - "water sapphire" or "lynx sapphire".

Sapphires and rubies are not used to make large jewelry. It really is. Most often, the aforementioned stones are used as inserts into rings and earrings, since rubies and sapphires are quite expensive, and they cannot boast of large sizes. But there are exceptions.
Large sapphires are more common than rubies. For example, at the Smithsonian Institution there is a star sapphire "Black Star of Queensland" (733 carats). Two more large star sapphires can be seen in the New York Museum of Natural History: The Star of India (blue, 536 carats) and the Midnight Star (black, 116 carats). The busts of the presidents of America (A. Lincoln (2302 carats), J. Washington (1997 carats) and D. Eisenhower (2097 carats)), installed in the Museum of Washington, are made of sapphire crystals. The Diamond Fund of Russia has a sapphire weighing 258.18 carats.
Large rubies, as mentioned above, are extremely rare, therefore they are usually very expensive. The Burmese Museum in London currently houses an untreated Burmese ruby ​​(3450 carats), an even larger crystal (of low gem quality) 14 cm high and weighing 8500 carats is cut in the shape of the Liberty Bell. The most famous asteria (star rubies) in India are Rajarathna with a six-pointed star (2475 carats) and Niilanjahi with a twelve-pointed star (1370 carats).

The fluorescence effect is characteristic only of natural rubies. Misconception. A fluorescent doublet located in the red region of the visible spectrum, caused by both sunlight and ultraviolet rays, is observed in both natural and synthetic rubies.

Carbuncle is synonymous with ruby. In ancient times, "carbuncles" were most often called blood-red, with a fiery sheen, pyropes (a kind of pomegranate). However, the same term was used to refer to red spinel (which, like pyropes, was sometimes confused with ruby) and, in fact, rubies.

The darker the ruby ​​or sapphire, the more valuable it is. A colored gemstone should be neither overly light nor overly dark. The most expensive are the pigeon blood ruby ​​and cornflower blue sapphire. The presence of a gray or brown tint can significantly reduce the price of a stone.

If a gemstone has no visible inclusions, then it is artificial. Indeed, most gemstones have minor inclusions of other minerals inside (the number of such inclusions determines the price of the stone). Perfect stones of absolute purity are extremely rare. The cost of such crystals is very high. Also, remember that a good gemstone should not have inclusions visible to the naked eye.

Watch the video: How to make Synthetic RubySapphire at home Update (October 2020).