Topaz- hardness 8, birthstone of November and Astrological stone for Sagittarius. Colour: colourless, pale yellow, pale blue, pink. Topaz- name comes from Greek word topazion which may originate from Sanskrit tapas meaning fire. Normally a dark yellow colour, topaz crystals comes in shades of pink, blue, clear. The most sought after colours are pale pink and honey coloured, pale blue crystals are normally irradiated with gamma rays to darken the colour. Commercial name London Blue Topaz- Topaz with deep sky blue colour. Topaz is found all over: Brasil, Sri lanka, Russia, America, Mexico, Australia.