People sincecrall loved to decorate themselves. At first it was simple wreaths and necklaces from bright colors, then shells and beautiful minerals. Later, people learned how to handle natural, often unbroken crystals so that they became genuine treasures. This article we will talk about sapphires.
Main characteristics
Sapphire is one of the most beautiful and expensive natural gems, and it was almost always, from ancient times, when a person learned how to produce and treat these natural crystals.
Sapphire, as well as its fellow Ruby, refers to corundum - mineral, the basis of which is an aluminum oxide with various impurities, which are painted crystals into different colors. Distinguish classic and fantasy sapphires. The first group is the crystals of the blue color of a variety of shades. Well, the second one is attributed to all other corundes, except saturated-red - these are rubies.
The main parameters for which the color of precious stones are estimated, including sapphires, is a shade, color saturation and lightlock. The standard shade for fantasy sapphires is not in connection with the variety of their colors. And for classic blue crystals the best is the best cornflower - the color of sapphires mined in Kashmir.
Physical properties of Corunda
| Indicators | Meaning |
| Composition | Aluminum oxide with various inclusions |
| Moos hardness | 9 (second after diamond) |
| Transparency | Varies from opaque to transparent |
| Density, g / cm3 | 3.95 - 4.0 |
| Refractiveness coefficient | 1.766 - 1,774. |
| Electrical conductivity | dielectric |
Sapphires are considered strong talismans. Many sources write that they help from a bad eye, damage and deception, contribute to the acquisition of wisdom and calm. He was loved to wear navigators and travelers, especially they loved asteria stones (star sapphires).
It is also believed that the wearing of corundum is beneficial on people suffering from insomnia, rheumatism, epilepsy and various infections.
What does the shade depend on?
The color of the stone depends on its composition. Even the small presence of extraneous impurities can radically change the colors and purity of the sapphire.The effect of impurities on the color of the mineral
| Impurities | Stone color |
| Titanium and iron salts | Blue, blue, bluish gray |
| Increased content of titanium | Orange |
| Oxide vanadium | Purple or reddish |
| Increased iron content | Sine-green |
| Nickel oxide | Yellow |
| Magnesium, zinc and cobalt salts | Green |
| Chromium, Iron and Titanium Salts | Pink, purple, lilac |
| Hematite (in the form of lamellar crystals) | Brown |
| Almost complete absence of foreign inclusions | Colorless, white |
Color saturation largely depends on the number and percentage ratio of foreign inclusions. According to the simplified scheme, the blue sapphires are divided into bright, medium and light stones. Professionals are used when evaluating crystals of 5 degrees of lightweight and 3 categories of saturation.
Main color gamma
Colored sapphires are of a wide variety of coloring, excluding, as already mentioned above, a rich red color.
The most expensive are the saturated blue gems, followed by the stones of pinkish-orange colors ("pad apartments", which means "lotus flower"), then purely pink crystals. Yellow transparent sapphires and blue opaque asterias (stones, on the ground surface of which a picture of a 6- or 12-beam star is clearly visible) occupy a 4th place in the high cost. The step below is orange, green, purple gems, as well as sapphires with alexandrit effect - that is, changing coloring depending on the lighting. Wholes are cheaper than colorless stones, as well as black simple and star. In fact, not quite correctly call black sapphires black - they are blue, just because of the high saturation of the color they seem dark and opaque.
Sometimes there are crystals, one part of which is painted in one color, for example, blue, and the second one - in the other, for example, yellow. Such stones are called polychrome, or multicolored, they are quite highly appreciated due to rarity.
How to choose?
When choosing jewelry with any precious or semi-precious stones, require a certificate confirming the natural origin of the mineral. Nowadays, many precious stones grow artificially in autoclaves. The naked eye is impossible to distinguish them from natural. But there is a significant difference in price, because natural sapphires are very very expensive, and this is already creating ample opportunities for all sorts of fraudsters. Therefore, do not forget about certificates, and in the case of the acquisition of large stones, do not be lazy to order an examination, because it is very easy to deceive.
There is an easy way to check the natural nature of the stone: direct the light of the ultraviolet lamp on it. Natural crystals at the same time should be greened, and synthetic - no.
When viewing a certificate, pay attention to the assessment of the stone, for example, 1/2. The first figure indicates the color of the stone (1 - blue), and the second - quality category (depending on the purity of the stone and the level of transparency of the crystal). Quality categories of only 4. The first includes the stones of the highest purity and transparency, in which there are practically no defects. The second includes transparent sapphires with worse quality - with minor defects or with an overwhelmed color. In opaque stones of the third category, defects can be seen with the naked eye. Well, the fourth group includes turbid crystals with pronounced shortcomings.
Also, do not forget to see, there is a stone to the refined or not. To improve the quality, most natural sapphires are treated thermally, that is, heated. This allows you to change the color of the stone, increase its transparency, etc. On the physical properties of the mineral, this treatment does not affect the non-aggravated natural sapphires are much higher than treated.
Look through the stone on the light, the best natural. Inside the crystal, microcracks can often be seen, which reduce the quality, and, accordingly, the price of the stone. Rate the cut stone. Sometimes due to improper processing or unfair grinding, the appearance of the gem seems to fill, without reflecting all its beauty.
The price of crystals is also highly dependent on the country of their production. The most expensive are the stones mined in Kashmir, on Sri Lanka and in Tanzania. Burmese and Thai crystals are followed by the second. Next - mined in all other countries of the world, except Australia, as Australian sapphires are located on the lower line of the price rating of these minerals. It should be noted that the Kashmir deposit has already been developed and closed. In the Russian Federation there are also several fields of Corundov - on the Kola Peninsula (blue, greenish, cornstorm) and in the Urals (gray-blue).
Also in Russia, as in other countries, artificial corundes are produced, because these stones are applied not only in jewelry, as well as in many industries.
About the properties of Sapphire is described below.