The equivalent of synthetic gems in the world of pearls, cultured pearls are formed under the same conditions as their natural counterparts and are chemically and physically the same as the natural products, with a few tell-tale differences.
La Paz pearls have a strong red reaction in LW. Dyed black pearls may show variable reactions under LW but never the same as natural. Natural black pearls may be weak to moderate red, orangish red, or brownish red in LW. Freshwater pearls always glow yellowish white in X-rays. Cultured pearls may have no reaction or the same reaction as naturals in LW. The fluorescence of natural pearls may range from inert to strong light blue, yellowish, greenish, or pinkish in both longwave (LW) and shortwave (SW) ultraviolet light (UV). “Perliculture” or pearl farming makes it possible to produce pearls in greater quantities and larger sizes than can grow in nature. As natural sources reached exhaustion, the modern era of cultured pearl production began in Japan around 1910. Even today, they’re extremely rare and can command a ransom. Natural pearls almost disappeared from the market in the late 1800s due to over-harvesting. This creates a pearl’s distinctive surface luster. The thin layers of nacre create a kind of diffraction grating through which light must pass. Nacre is composed of the mineral aragonite with an organic binder called conchiolin. As a result, the creature’s shell producing system begins coating the irritant with nacre (NAY-ker), the shiny substance found on the interior of most shells. How Does a Pearl Form?įor a pearl to form, an irritant must get deep enough inside of the shell that the mollusk cannot expel it. N = 1.53-1.69, but not observed usually vague shadow edge in this range.įrom the Old French perle, Medieval Latin perla, and Classical Latin pernula or perna for pearl.įormed within various species of living bivalve mollusks in both salt and freshwater.Ī natural pearl, from an oyster found in Tamalas Bay, CA.
These proportions are variable.Īggregate, if not opaque. Aragonite in nacre ranges from 0.155–0.156.įluorescent, UV-Long, UV-Short, X-ray Colorsīleaching, dyeing, surface coating, radiation.īleaching, Dyeing, Irradiation, Surface CoatingĬaCO 3 (aragonite, the outer layer) about 82-86%, conchiolin 10-14%, water 2%. See “Identifying Characteristics” below for more information.Ģ.6–2.78 conch pearls, 2.85 cultured pearls, 2.72-2.78, that is, heavier than most naturals.
#Misshapen pearls full
There are sometimes two overtone colors, one seen on the surface in full view, the other at the edge. The rest of the color is due to the body color. The orient is the color seen as reflected by a diffuse light source. Pearl color is the result of a body color and an overtone color or orient present as a lustrous sheen. The aragonite in the nacre of a pearl is orthorhombic, with minute crystals radially oriented and a concentric structure. Licensed under CC By 2.0.Ĭonch Pearl, Freshwater Pearl, Saltwater PearlĪmorphous.
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