Beryl 7-3/4 2.709-2.81 Corundum 9 3.90-4.16 Diamond 10 3.502-3.564 Jade 7 3.300-3.381 Opal 5-1/2-6-1/2 2.160-2.283 Phenakite 7-3/4 2.965 Quartz 7 2.670 Rock-crystal 7 2.521-2.795 Sapphire 9 4.049-4.060 Spinel 8 3.614-3.654 Topaz 8 3.500-3.520 Tourmaline 7-1/4 3.029 Zircon 7-1/2 4.700-4.880 YELLOW STONES. _Hardness._ _Specific Gravity._ (See Chapter VII.) (See Chapter VIII.) Amber 2-1/2 1.000 Beryl 7-3/4 2.709-2.810 Chrysoberyl 8-1/2 3.689-3.752 Chrysolite 6-7 3.316-3.528 Corundum (the yellow variety known as "Oriental Topaz" [not "Topaz"], see below) 9 3.90-4.16 Diamond 10 3.502-3.564 Garnets (various) 6-1/2-7-1/2 3.4-4.5 Hyacinth (a form of Zircon) 7-1/2 4.7-4.88 Quartz (Citrine) 7 2.658 Sapphire 9 4.049-4.060 Spinel 8 3.614-3.654 Topaz (for "Oriental Topaz," see above) 8 3.500-3.520 Tourmaline 7-1/4 3.210 BROWN AND FLAME-COLOURED STONES. _Hardness._ _Specific Gravity._ (See Chapter VII.) (See Chapter VIII.) Andalusite 7-1/2 3.204 Diamond 10 3.502-3.564 Garnets (various) 6-1/2-7-1/2 3.40-4.50 Hyacinth (a form of Zircon), see below 7-1/2 4.70-4.88 Quartz (smoke coloured) 7 2.670 Tourmaline 7-1/4 3.100 Zircon (Hyacinth) 7-1/2 4.70-4.88 RED AND ROSE-COLOURED STONES.