Crystal and stones » chrysoberyl

Chrysoberyl

precious stones — Wed, 16 Sep 2009 15:54:00 +0000

There are certain stones and other minerals which, owing to their possession of numerous microscopically fine cavities, of a globular or tubular shape, have the appearance of “rays” or “stars,” and these are called “asteriated.”

Several of such stones have been discussed already in the last chapter, and in addition to these star-like rays, [...]

Green gemstones

precious stones — Wed, 16 Sep 2009 15:20:47 +0000

Green gemstones

Hardness. Specific Gravity.

Aquamarine 7-3/4 2.701-2.800 Chrysoberyl 8-1/2 3.689-3.752 Chrysolite 6-7 3.316-3.528 Chrysoprase (Quartz) 7 2.670 Diamond 10 3.502-3.564 Dioptase 5 3.289 Emerald and Oriental Emerald 7-3/4 2.690 Euclase 7-1/2 3.090 Garnet (see also Red Garnet) 6-1/2-7-1/2 3.400-4.500 Heliotrope (Chalcedony) 6-1/2 2.598-2.610 Hiddenite (a variety of Spodumene) 6-1/2-7 3.130-3.200 Jade 7 [...]

Yellow Stones

precious stones — Wed, 16 Sep 2009 15:02:53 +0000

Yellow Stones

Hardness. Specific Gravity.

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”) 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 .614-3.654 Topaz (for “Oriental [...]

Heat-rays to precious stones

precious stones — Wed, 16 Sep 2009 14:30:16 +0000

Another method of isolating certain stones is by the action of heat-rays.

Remembering our lessons in physics we recall that just as light-rays may be refracted, absorbed, or reflected, according to the media through which they are caused to pass, so do heat-rays possess similar properties.

Therefore, if heat-rays are projected through precious [...]

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 [...]

Pleochroism and colour of minerals

precious stones — Wed, 16 Sep 2009 13:13:11 +0000

Color is one of the most wonderful effects in nature. It is an attribute of light and is not a part of the object which appears to be coloured; though all objects, by their chemical or physical composition, determine the number and variety of vibrations passed on or returned to the eye, thus fixing their [...]

Origin of precious stones

precious stones — Wed, 16 Sep 2009 12:45:01 +0000

Though the origin, formation, composition, characteristics and tests of each stone will be examined in detail when dealing with the stones seriatim, it is necessary to enquire into those particulars of origin which are common to all, in order thoroughly to understand why they differ from other non-metallic and metallic minerals.

At the very commencement [...]