The color of a stone is the most unreliable characteristic for determining its type. There are related groups of minerals, the color of which is different, and there are species that are very distant from each other, similar in appearance.
Instructions
Step 1
Most often, the color that precious stones have depends on microscopic particles of impurities of metal oxides that are not included in the chemical formula of the mineral and are not always determined with the most accurate chemical analysis. The spectroscope is more sensitive to such impurities; some elements can be detected by looking at the spectrum of light emitted through a stone. Iron is one of the most effective dyes. In the form of an oxide, its presence gives yellow tints, in the form of nitrous oxide, you can get a bottle-green color. Chrome turns rubies red and emeralds green. Copper combines with hydroxyl to create unique shades of turquoise. If turquoise has a greenish color, it is due to the presence of iron in it.
Step 2
Copper hydroxides, in addition to turquoise, create shades of minerals such as malachite, azurite and dioptase. Titanium in the mineral gives it a blue color, and lithium colors an unstable pink. The minerals rhodonite and rhodochrosite have a unique pink color, which is given to them by manganese. In the richness of color and shade, such chemical elements as cobalt, nickel, vanadium, cesium, gallium also play an important role. Gemstones are called idiochromatic if their coloring agent is included in the chemical formula of the mineral, and allochromatic if the coloring element is an impurity.
Step 3
Stones of the same type often differ significantly in color. It depends on the impurity of the metal oxide. An example is corundum: pure alumina produces white corundum, also called sapphire, and chromium oxide produces red corundum known as ruby. The combination of iron and titanium eventually gives rise to blue corundum - the rarest and most expensive of sapphires. Even diamonds, due to a variety of impurities, have different shades, they are yellowish, bluish, greenish, gray, brown, black, and sometimes intensely colored stones. It all depends on the same oxides of various metals present in the mineral to a greater or lesser extent.
Step 4
Alexandrite changes its color depending on the lighting: it is dark green during the day, it turns crimson in the evening. The same thing happens with deep purple amethysts, which turn blood red in artificial light. Turquoise changes shades depending on temperature, humidity and the impact of different environments on this stone.
