Crystal and stones » Pyrope

Silicates

precious stones — Wed, 16 Sep 2009 16:14:00 +0000

The chief of these are the garnets, crystallising in the cubic system, and anhydrous.

The garnet is usually in the form of a rhombic dodecahedron, or as a trisoctahedron (called also sometimes an icosatetrahedron), or a mixture of the two, though the stones appear in other cubic forms.

In hardness they vary from [...]

Pyrope to Diamond

precious stones — Wed, 16 Sep 2009 14:13:01 +0000

Group C. Stones whose specific gravity lies between 3.50 and under 3.70.

Pyrope (average) 3.682 Chrysoberyl 3.689 and occasionally to 3.752 Spinel 3.614 ” 3.654 Kyanite 3.609 ” 3.688 Hessonite 3.603 ” 3.651 Diamond 3.502 ” 3.564 Topaz 3.500 ” 3.520

Specific gravity of gemstones

precious stones — Wed, 16 Sep 2009 13:53:09 +0000

The fixing of the specific gravity of a stone also determines its group position with regard to weight; its colour and other characteristics defining the actual stone.

This is a safe and very common method of proving a stone, since its specific gravity does not vary more than a point or so in different [...]