Opal (various) 5-1/2-6-1/2
Nephrite 5-3/4
Chrysolite 6-7
Felspar 6
Adularia 6
Amazon stone 6
Diopside 6
Iron pyrites 6
Labradorite 6
Turquoise 6
Spodumene 6-1/2-7
The Chalcedony group which embraces the Agate,
Carnelian, etc. 6-1/2
Demantoid 6-1/2
Epidote 6-1/2
Idocrase 6-1/2
Garnets (see also "Red Garnets" below) 6-1/2-7-1/2
Axinite 6-3/4
Jadeite 6-3/4
Quartz, including Rock-crystal, Amethyst, Jasper,
Chrysoprase Citrine, etc. 7
Jade 7
Dichorite (water sapphire) 7-7-1/2
Cordierite 7-1/4
Red Garnets (see also Garnets above) 7-1/4
Tourmaline 7-1/4
Andalusite 7-1/2
Euclase 7-1/2
Staurolite 7-1/2
Zircon 7-1/2
Emerald, Aquamarine, or Beryl 7-3/4
Phenakite 7-3/4
Spinel 8
Topaz 8
Chrysoberyl 8-1/2
The Corundum group embracing the Ruby, Sapphire, etc. 9
Diamond 10

(See also list of stones, arranged in their respective colours, in
Chapter XII.)

The method of testing is very simple. A re