Conchiolin & Calcareous Coral
There are two distinct types of coral: Calcareous Coral which is primarily composed of calcite, and Conchiolin Coral which is primarily composed of protein.
Conchiolin: Dark substance secreted by a mollusk for protection during cultivation.
Crown: Denotes the top part of the gemstone.
Culet: The lowest part of a gem.
Conchiolin
The first layer secreted by a mollusk to ease the discomfort caused when a foreign substance gets lodged in the mantle tissue. Very important as it binds the nacre to form the pearl.
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Conchiolin: Organic matter layed out in thin sheets, on the external side of the shell. Also a component of nacre.
Conchiolin
The protein layer that is secreted by a mollusc on the nucleus. It works as the adhesive of aragonite, allowing more layers to build.
Concretion ...
Nacre is composed of alternate layers of the aragonite form of calcium carbonate and conchiolin. The undulating grain of mother of pearl is the result of seasonal fluctuations in the mollusk's diet.
Pearls are composed partly of the mineral substance calcium carbonate (chemically the same as marble) and partly of a tough, horny substance of organic nature called conchiolin.
Nacre is a mixture of crystalline calcium carbonate and conchiolin. Native Cut: Often referred to as Indian cut. This fashion of diamond cut is very rough. The diamonds appear as thin slivers. Few facets if any are made.
This changes the color of conchiolin (permanent) and renders the pearls virtually indistinguishable from natural or cultured blacks.
What we commonly call pearls are irritant-induced secretions of mollusks which are covered with lustrous nacre (a combination of aragonite or calcite and conchiolin protein).
As a response to an irritating object inside its shell, the mollusk will deposit layers of calcium carbonate in the form of calcite and held together by an organic horn-like compound conchiolin.
Each layer of nacre that covers it has a layer of conchiolin in between. These layers do not always cover the pearl completely. This leads to imperfections.
The pearl is composed of conchiolin and calcium carbonate (in the form of minuscule prisms of calcite or aragonite) that is secreted by the mantle of the mollusc and is deposited as nacre in very many thin concentric layers to surround some foreign ...
The oyster surrounds the intruder with epithelial cells, forming a sac, and then secrets a mixture of nacre and conchiolin onto it.
Sensing the object or damage, the living organism within the mollusk secretes calcium carbonate in the form of aragonite, and the binding protein conchiolin.
Mantle - Mantle tissue is the soft tissue found in an oyster and is the medium for the cells that start the production of conchiolin and nacre. In cultured pearls, a round bead is inserted into the oyster with a piece of mantle tissue.
Nacre - is the layers of aragonite and conchiolin that form around the pearl's centre. The thicker the nacre, the longer a pearl will typically last.
nacre
The crystalline substance made of aragonite and calcite crystals bound together by conchiolin, which mollusks like oysters secrete around foreign objects within their shells, layers of which eventually form a pearl ...
The mollusk secretes calcium carbonate to surround the irritant, which accumulates in layers of aragonite and conchiolin. This layered formation causes the refraction of light that gives pearls their distinctive appearance.
Chemical Composition: mostly calcium carbonate, with some conchiolin and water
Crystal System: n/a
Hardness: n/a
Specific Gravity: 2.60-2.78
Geographic Origins: Japan, Australia, Persian Gulf, Venezuela, California, Florida ...
also known as mother-of-pearl, is the iridescent material secreted by a mollusk to protect it from irritants, eventually creating a pearl. It also lines the inside surface of an oyster shell. It is made mostly of calcium carbonate and conchiolin.
Blue Pearl: A variety of pearl that is lead-greyish owing to a thin crust over a layer of conchionlin near the surface, or a dark kernel rich in conchiolin.
Mantle tissue is the soft tissue found in an oyster or mollusk and is the medium for the cells that start the production of conchiolin and nacre.
marcasite ...
Mother of Pearl or Nacre is the iridescent substance that forms the lining of the shells of some fresh-water and some salt-water mollusks. It is composed of alternate layers of the aragonite form of calcium carbonate and conchiolin. Hardness: 3.
 See also: Color, Jewel, Pearl, Water, Pearls
  
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