Gem and gemstone
A gemstone or gem is a piece of mineral , which, in cut and polished form, is used to make jewelry or other adornments.
It is also called as precious or semi-precious stone.
Gemstones are classified into 3, they are
1. Groups,
2. Species, and
3. Varieties.
For example, ruby is the red variety of the species corundum , while any other color of corundum is considered sapphire.
Emerald (green), aquamarine (blue), red beryl (red), goshenite (colorless), heliodor (yellow), and morganite (pink) are all varieties of the mineral species beryl.
Gems are characterized in terms of their
1. Refractive index,
2. Dispersion,
3. Specific gravity,
4. Hardness,
5. Cleavage,
6. Fracture, and
7. Luster .
Gems exhibit pleochroism or double refraction . They may have luminescence and a distinctive absorption spectrum .
Material or flaws within a stone may be present as inclusions.
Gem cutting:
The process of cutting and polishing gems is called gemcutting or lapidary. A person who cuts and polishes gems is called a gemcutter or as lapidarist.
A raw Gemstone or a gemstone material that has not been cut or polished is referred to as “rough” . Rough material that has been lightly hammered to knock off brittle, fractured material is said to have been cobbed .
Gems are cut by:
All gems are cut and polished by progressive abrasion using finer and finer grits of harder substances. Diamond, the hardest naturally occurring substance, has a Mohs hardness of 10 and is used as an abrasive to cut and polish a wide variety of materials, including diamond itself.
Silicon carbide, a manmade compound of silicon and carbon with a Mohs hardness of 9.5, is also widely used for cutting softer gemstones. Other compounds, such as cerium oxide, tin oxide, chromium oxide, and aluminum oxide, are frequently used in polishing gemstones.
Lapidary Techniques:
Several common techniques are used in lapidary work:
sawing
grinding
sanding
lapping
polishing
drilling
tumbling
Using the techniques listed above, gemstones aretypically fashioned into one of several familiar forms:
cabochons
faceted stones
beads and spheres
inlays
intarsias and mosaics
cameos and intaglios
sculptures
GemAndGemstone specialize in Loose precious gems and semi precious gemstones. They provide cut/faceted gems, gemstones cabochon/cabs, gemstone beads or brilotte at a very economical price.
About the Author
GemAndGemstone specialize in Loose precious gems and semi precious gemstones. They provide cut/faceted gems, gemstones cabochon/cabs, gemstone beads or brilotte at a very economical price.
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