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Plastic
Article Id - AGG0000161
 
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Nature of Material: plastic is an amorphous man made material consisting of long chain- ¬like molecules (polymers); chemical com¬- position varies, but is usually rich in carbon and hydrogen.
 

Appearance: transparent to opaque all colors; commonly used in fashion jewelry and as an imitation for various gems, particularly organic materials such as amber, coral, jet, ivory, etc.; also produced with a structure that causes play-of-color like that seen in opal.

Phenomena: asterism (generally a crude simulation on the surface, unlike true asterism from light-scattering inclusions), adularescence, aventurescence, chatoyancy, orient (simulated by coatings on plastic imitation pearls), iridescence, play-of-color.
 
Variety and Trade Names
May be specified by commercial or generic names such as Lucite, Plexiglas, celluloid, Bakelite, acrylic, etc. Amberum – plastic with grass, insects, & other inclusions like amber.
 
Misnomers: none known
Typical Size Range: all sizes
Typical Cutting Styles: all styles (usually molded)
 
 
 
Identification
Optic Character: SR, strong ADR and strain colors common
Refractive Index: usually between 1.460 and 1.700
Birefringence: none
Specific Gravity: usually between 1.05 and 1.55
Polish Luster: waxy to vitreous
Fracture: conchoidal to uneven
Luster: dull to vitreous
Cleavage: none

Identifying Characteristics 
Gas bubbles, flow lines, mold marks, "orange-peel" effect, concave facets, rounded facet junctions, warm to touch, often acrid odor to hot point, light heft


Method of Manufacture: heating and pressurizing chemicals until polymerization occurs Key
Separations: plastic from glass - hot point, SG, hardness
Hardness: 1½ to 3
Toughness: fair

Market
Availability: plentiful
Public Recognition: well known
Recommended Disclosure: Avoid rough handling, heat, and chemicals
 
 
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