COLOR
The color of a stone results from the absorption and reflection of certain wavelengths of the light spectrum. If a color spectrum is absorbed, the color will reflect the stone will consist of the mixture of remaining colors.
The absorption spectrum of colors is caused by the presence of metals within the stones. However, their presence is so small it does not appear in the chemical formula. This is the case of iron, responsible for the blue of aquamarine, but there is no mention in the chemical composition (Be3 Al2 Si6O18).
Color is the main criterion for determining the value of colored stones. To improve the quality, intensity and purity, the majority of them are the subject of treatment. The most common are heat, oil impregnation and irradiation. Their main disadvantages are that they are difficult to detect (irradiated stones can be sold fraudulently as untreated) and they are not always permanent (the color is likely to lose its purity and intensity with time). Untreated stones are more popular and their value is necessarily greater than that of treated stones
Classification of gems by color
Red
Andalouzite
|
Red beryl
|
Diamonds
|
Almandine garnet
|
Pyrope garnet
|
Rhodolite garnet
|
Spessartite garnet
|
Kunzite
|
Morganite
|
Rubellite
|
Ruby
|
Pink Sapphire
|
Scapolite
|
Spinel
|
Zircon
|
Diamond
|
Garnet hessonite
|
Sapphire Padparadsha
|
Scapolite
|
Spinel
|
Topaz
|
Tourmaline
|
Zircon
|
Yellow
Beryl
|
Chrysoberyl
|
Citrine
|
Diamond
|
Garnet hessonite
|
Noble orthoclase
|
Sapphire
|
Scapolite
|
Sphene
|
Zircon
|
Green
Alexandrite
|
Diamond
|
Emerald
|
Demantoid garnet
|
Tsavorite garnet
|
Peridot
|
Sapphire
|
Scapolite
|
Sphene
|
Tanzanite
|
Tourmaline
|
Zircon
|
Blue
Aquamarine
|
Bénitoïte
|
Sapphire
|
Spinel
|
Tanzanite
|
Tourmaline indigolite
|
Zircon
|
Purple
Amethyst
|
Rhodolite garnet
|
Kunzite
|
Sapphire
|
Scapolite
|
Spinel
|
List of main components dyes
Element dye
|
Gems
|
Chromium
|
Ruby, Emerald, Garnets pyrope, grossular and uvarovite
|
Copper
|
Dioptase, Malachite, Azurite
|
Iron
|
Sapphire, Aquamarine, Citrine, Garnet Almandine
|
Manganese
|
Morganite, Pink Tourmaline, Garnet spessartite
|
Nickel
|
Chrysoprase
|
Titanium
|
Blue Sapphire
|
Vanadium
|
Green beryl, blue zoisite
|
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