Chemical Composition of Gem Stones

Gem Name	Chemical Composition	Hardness	Colour	Location
Diamond	Carbon………..10	10	Colourless, Yellow, Red, Blue, Brown, Pink, Green, Black	India, Brazil, S.Africa, Australia
Ruby	Alumina……98.5 Oxide of Iron..1. 0 Lime…………0.5	8.5 To 9	All Red shades	Burma, Siam, Ceylon
Sapphire	Alumina……98.5 Oxide of Iron...1.0 Lime…………0.5	9	All Blue shades	Burma, Siam, Ceylon, Kashmir, Montana, Australia
Emerald	Silica….……68.0 Alumina…....18.3 Glucina.……12.2 Magnesia….. 0.8 Soda………. 0.7	7.5 to 8	Emerald Green	India S. America Siberia
Aquamarine	Silica….……68.0 Alumina…....18.3 Glucina.……12.2 Magnesia….. 0.8 Soda………. 0.7	7.5 to 8	Colourless, Blue, Green, Yellow	India S. America Siberia
Spinel	Alumina…..71.99 Magnesia. 28. 01	8	Red, Blue, Green, Pink, Orange, Brown, Black	Ceylon, Siam, Burma
Tourmaline	Silica combined with oxides or iron, magnesium, manganese, and aluminium, boron in different proportions. Very variable	7 to 7.5	Red, Blue, Green, Yellow, Brown, Black	California, Siberia, Ceylon, Ava, Brazil