Precious Stones - Chemical Composition and Colours

important precious stones

Stone Colour & Chemical Composition
Diamond Transparent
Ruby Pink to Red
Corundum (Aluminium oxide Al2O3)
Emerald Green
Beryl (Be3Al2(SiO3)6)
Sapphire Blue
Corundum (α-Al2O3)
Amethyst Violet
Quartz (Silicon dioxide SiO2)
Opal Variety of colours
Hydrated silica (SiO2·nH2O)
Turquoise Blue to greenish
Hydrated copper and aluminium phosphate [CuAl6(PO4)4(OH)8·4H2O]
Topaz Variety of colours
Aluminum silicate containing fluorine (Al2(F,OH)2SiO4)
Lapis Lazuli Deep blue
Metamorphic rock with mineral lazurite as its chief constituent
Aquamarine Pale greenish blue or bluish green
Beryl (Be3Al2(SiO3)6)
Morganite Pink to orange-pink
Beryl (Be3Al2(SiO3)6)
Onyx Bands of black and white
Silicon dioxide (SiO2))

Other Precious Materials

Material Colour & Chemical Composition
Pearl White (other colours are also possible but rare)
Argonite (Calcium Carbonate CaCO3))
Ivory White
Dentine (Ca10(PO4)6(CO3)·H2O))

Some Interesting Facts

  • Diamond is the hardest substance known. It is an allotrope of carbon.
  • Weight of gemstones like diamonds, rubies, emeralds, and sapphires is typically measured in carats.
  • The carat weight of these gemstones refers to the stone's mass, where one carat is equivalent to 0.2 grams or 200 milligrams.
  • The largest producer of diamonds is Russia as of 2021.
  • Kimberley in South Africa is famous for the 19th century diamond rush. The Kimberley mine yielded millions of carats of diamonds in its over 40 years of operation.
  • Cullinan is the largest gem-quality rough diamond ever found weighing about 3106 carats. It was later cut into several smaller diamonds, the largest of which was known as the Great Star of South Africa (weight 530.4 carats).
  • The largest producer of diamonds in India is Madhya Pradesh. Majhgawan mine in Bundelkhand area is famous for diamonds.
  • The largest producer of ruby is Myanmar.
  • The largest producer of emeralds is Colombia.
  • The largest producer of opals is Australia.
  • Elephants are the main source of ivory, but some other animals like walruses, narwhals, hippopotamus and warthogs also yield ivory.

Note: The availability and production levels of gemstones and pearls can vary over time, as new deposits are discovered and mining activities evolve.


Test yourself

Colour of Emerald   

Composition of Pearl   

Which stone is hydrated silica?   

Which contains only one element?   

Which may occur in variety of colours?   

Colour of Amethyst is   

Which contains Corundum?   

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