SAPPHIRE. 23 
S!(il>l)jLir('s or coniiidinn ffpiiis. 
Oriental or true ruby_ _ _ Red of various shades. 
Pink sapphire Rose or pink. 
Oriental amethyst Purple. 
Oriental sapphire Blue of various shades. 
Opaline _. i 
Girasol iPale blue or hhiish white. 
Hyaline J 
Oriental emerald Green. 
Oriental topaz Yellow. 
White sapphire ) 
Diamondspar . jColorless. 
Star sapphire 1 
Chatoyant lOpalescent. 
Asteria J 
All these varieties of corundum gems have been found in the United 
States. The North Carolina and Montana cornndums excel in variety 
of color those from other localities in this country, having been 
found ruby-red, rose, and all intervening shades, pink, sapphire-blue, 
dark-blue to pale-blue, emerald-green, and green of various shades, 
violet to purplish, yellow of various shades, brown, gray, black, and 
colorless. 
INDICES OF REFRACTION OF GEMS. 
In index of refraction corundum is lower than a number of the 
commoner gem minerals. In tlie following table the relative posi- 
tion of the corundum is shown : 
Gem. 
Li=Red. 
Na=Yellow. 
Tl= Green. 
Diamond 
Zircon 
Almandite (garnet).- 
Pyrope (garnet) 
Sapphire (corundum) 
Riiby (corundum) .. 
Rhodolite (garnet) _ _ _ 
Spinel ruby (spinel) _ _ 
Hiddenite.. 
2. 4135 
1.8000 
1.7776 
GJ E 
1.7678-1.7598 
1.7675-1.7592 
1.7121 
2. 4195 
00 E 
1.9236-1.9682 
1.8056 
1.8141 
2. 4278 
1.8113 
1.8288 
Descloix. 
Pratt. 
Descloix. 
Do. 
Do. 
1.7496 
1.7155 
/f=1.669 
/i= 1.615 
^ £ 
1.6374-1.6196 
1.5893-1.5821 
1.5841-1.5780 
1.5441-1.5532 
Pratt. 
Topaz 
00 E 
1.6409-1.6232 
1.5921-1.5848 
Tourmaline 
Aquamarine (beryl) _ 
Emerald (beryl) 
GO £ 
1.6347-1.6172 
1.5862-1.5791 
1.5391-1.5480 
Do. 
Dufet. 
Amethyst 
1.5542-1.5636 
