corundum is composed of pure
alumina; its colouring is due to metallic
|oxide traces or inclusions. The color of sapphire, due to iron and titanium oxide, gives its best |
|effect under daylight. Electric light makes it often dark.|
|Gems are generally found in alluvium, but come either from basaltic
slags, or from metamorphic
blue Sapphire crystal single
23.3 x 16.6 mm.
Enhancement: none (N)
that this sapphire can be found only near one occurrence to
which the color of the stones is close to that of Kashmir. This type of
sapphire is thus much rarer than ruby.