The beauty of precious stones captivates. Specimens with the purest and brightest color are especially appreciated. In particular, the emerald should be green, the sapphire should be a piercing blue, and the ruby should be deep red. But the color of jewelry is most often due not to their own crystal lattice, but to the presence of impurities. They can give sapphire a green color and emerald bluish or yellowish.
The chemical formula of sapphire is very simple: Al2O3 (aluminum oxide). This mineral is used in the electronics industry due to its special semiconducting properties. In its pure form, it is colorless and translucent and is called "leucosapphire", since the word "leukos" is translated from Greek as "white". It is grown artificially for industrial purposes, since in nature these crystals almost always have impurities. Their content in precious stones is measured in mass percent, reflecting the ratio of impurity to the mass of "pure" stone.
Iron and titanium give the blue color, while vanadium adds a purple hue. Stones of bright blue, cornflower-blue color are most valued and quite rare. Their deposits are located mainly in Sri Lanka. The large amount of iron gives the sapphire a greenish color. Corundum, which contains a lot of iron oxide, turns yellowish.
Surprisingly, the crystal structure of rubies is the same as that of sapphires! That is, these are two different names for the same stone. They differ only in color. It is considered to be rubies only red stones with a purple hue (it is provided by an admixture of chromium), but in jewelry stores you can often find a tag with the signature "ruby" attached to a product with a pink stone. In fact, it would be correct to write "pink sapphire", but not all jewelry stores do this. Serious companies use color coordinates to describe the color of stones. It is the coordinates that indicate what is called sapphire and what is called ruby. Some color grading systems have their own standards.
Brooch-butterfly made of pink sapphire and diamonds / AP Photo / Laurent Gillieron
Emerald is a green variety of beryl that contains chromium. Beryl itself, like leucosapphire, is colorless. But impurity elements can paint it in different colors. So, iron can color beryl blue or yellow, vanadium green, manganese pink. In an emerald, the content of chromium dioxide can reach 2-2.5%. The presence of other impurities in the emerald (iron, vanadium) can slightly change the shade of the stone, and also indicate its deposit. For example, Ural emeralds are characterized by a high iron content, while Colombian emeralds are characterized by an admixture of vanadium.
Emerald / Depositphotos / Boykung
The diamond is considered the king of precious stones. It is not only the most valuable and beautiful gemstone, but also a superhard technical mineral, chemically resistant to aggressive media, it is a reference semiconductor for electronics, a model object for solid state physics, and also an indicator of high pressures and temperatures in earth sciences.
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Spring view of natural diamond / ANI & quot; FIAN-Inform & quot;
“The color of a diamond is most often associated with impurities and structural defects resulting from the entry of impurities. The most important impurity in a diamond is nitrogen, which gives the diamond a yellow tint. This element can be included in the structure of a gemstone in the form of single atoms or their groups. Diamonds containing nitrogen in the form of clusters account for about 98% of the total rough diamonds. The amount of nitrogen in such stones can be up to 0.3% of carbon atoms, and on average it is hundredths of an atomic percent. But in the form of single atoms in diamonds, nitrogen is rare. But this form of nitrogen gives the stone a bright yellow, the so-called "fantasy" color. Volumetric defects in the form of planes cause brown coloration, and in some cases - rare pink. Extremely expensive and rare blue diamonds are obtained due to the admixture of boron,"- explains Irina Yekimenkova, researcher at the Department of Mineralogy of the Geological Faculty of Moscow State University.
Diamond found in Sierra Leone
Diamonds that do not contain impurities used to be called "pure water" stones. It was believed that if you put a diamond in water, it would be invisible. In fact, the refractive indices of light near water and this beautiful mineral differ enormously, and the diamond will be perfectly visible.
VS2 diamond sold at Christie's for $ 4.9 million / Christie's
The history of many jewelry with diamonds, emeralds and corundums goes back centuries. Epochs, society, worldview changed, but these stones invariably attracted people with their ancient and mysterious beauty.
Olga Kolentsova