Pearl Paradise The Internet's Largest Collection of Fine Pearls - Shop Now! 80% Off Retail. Free Returns. Free Shipping. A+ Rating on BBB.

Unconfigured Ad Widget

Collapse

Announcement

Collapse
No announcement yet.

Pearl-Producing Mollusks (Molluscs)

Collapse
X
Collapse
  •  

  • Pearl-Producing Mollusks (Mollusks)

    Pearl-Producing Mollusks (Pearl-Producing Bivalves)

    Mollusks represent one of the world's earliest forms of animal life, and date back over 550 million years. Actual pearl-producing mollusks first appeared 530 million years ago, when mollusks developed shells. The scientific discoveries of pearl producing mollusks illustrate the intrinsic and irrefutable value of the world's most historically treasured organic gem.
    Abalone fossil from Mexico - photo courtesy of Baja Pearl Hunter



    Abalone are not bivalves nor part of the "Conchifera" sub-phylum; instead, they belong to the Gastropoda group and yet they also produce "true pearls".


    Scientific Classification of Pearl-Producing Mollusks

    Mollusks encompass the second largest phylum of the animal kingdom (there are over 128,00000 different species). The phylum is divided into two subphyla, only one of which contains species that produce pearls. Conchifera is the name given to the subphylum of mollusks that produces pearls. In this discussion, a pearl-producing mollusk is one that will produce jewelry-quality pearls.



    Which are the Pearl-Producing Mollusks?

    Although any of the mollusks within the Conchifera subphylum can produce pearl-like formations, most of them are not pearl producing mollusks. It is the fourth class of the Mollusca phylum, BIVALVIA, which is the most important for the formation of pearls. Other notable classes that produce pearls are the gastropods (2nd class) and cephalopods (5th class). According to the scientific classification system developed by Carl Von Linne in 1758, each species of mollusk is given a two-part Latin name: the genus and the species.

    Sometimes a third part will describe a sub-species, which may represent regional differences among a species of pearl-producing mollusk. Although the shell of each mollusk is important for identification and critical to pearl formation, it is the inner soft body (and nowadays also its DNA) of the mollusk that scientifically defines the species.


    The Evolution of Pearl-Producing Mollusks

    The figure below illustrates the evolutionary tree for the Phylum Mollusca. Not all pearl producing mollusks belong to a single family or group. Pearl producers are distributed across the evolutionary tree. The boxes that are shaded indicate classes of Conchifera that exhibit the pearl producing compound of nacre. Nacre is the tissue that lines the shell and creates the unique luster of pearls.
    Evolutionary Tree of Pearl Bearing Mollusks


    The widespread presence of nacre indicates one of two points:
    • Nacre is a primitive characteristic that has been lost and regained throughout the mollusks' evolutionary history.
    • The composition of nacre is unique within certain branches, and certain forms of nacre facilitate pearl production.
    If the latter were true, it could explain why certain species of mollusk produce more pearls than others.


    Pearl-Producing Mollusks are Not necessarily Oysters

    Most pearl-producing mollusks are bivalves, meaning their shells have two halves connected by a hinge, like a clam. Although there are approximately 20,000 species of bivalve mollusks, only relatively few of these species are used in pearl culturing to create commercial pearls.

    The term "pearl oyster", commonly used in the pearl trade, is in fact incorrect since pearl producing mollusks are not oysters. Though edible oysters can occasionally produce a "pearl", they are non-nacreous and of no commercial significance. Furthermore, for the safety of our teeth, "pearls" (actually known as "calcium concretions") in edible oysters are undesirable. Commercial edible-oyster farms are in fact shut down if "pearls" persist to form within them.

    Pearl oysters are actually more closely related to "scallops", "pen shells" and "hammer shells" than to oysters, all of these belonging to the Pteriomorpha sub-class of bivalves.


    The Anatomy of Pearl-Producing Mollusks

    The anatomy of a bivalve mollusk facilitates the production of pearls. Unlike a closed snail, or gastropod shell, a bivalve clamshell is open, and water filled, leaving more room for pearls to form.
    Anatomy of a Black-Lip pearl oyster


    Bivalves are also passive filter feeders meaning they maintain an open relationship with the environment by constantly circulating water to supply food. This process is critical for pearl production, since most natural pearls are formed as a reaction to a parasite attack within the shell. The open relationship of the bivalve structure increases the probability of foreign objects and creatures to enter, and the possibility of a natural pearl to develop.

    Gastropods are very Different

    In contrast, gastropods do not rely on water flow for food and are usually quite mobile, some are predators who deliberately hunt for prey and others scrape algae from rocks or graze from seaweeds.

    Gastropods are also able to expel foreign particles before they become a pearl's nucleus through movement. Mobility has been a difficult factor in culturing abalone pearls. Abalone pearls come from large, ear-shaped snails, whose movement often expels inserted nuclei.

    Abalone pearls have beautiful blue-green nacre and display gorgeous rainbow iridescence. Because of their irregular shapes and liquid iridescence, abalone pearls epitomize the beautiful canvas of nacre that creates singular beauty in each pearl.
    Natural Abalone Pearl




    Related Articles:
    Related Forum Threads:
    Last edited by CortezPearls; 04-05-2021, 04:38 PM. Reason: Edited text and added images
      Posting comments is disabled.

    Categories

    Collapse

    article_tags

    Collapse

    Latest Articles

    Collapse

    • Mabe Pearl Grading - 7) Dome Height
      by CortezPearls
      Part of the beauty of a Mabe pearl comes from its “dome” (height). When a Mabe pearl displays a low dome it most closely resembles a piece of mother-of-pearl shell than an actual pearl. Unfortunately, many Mabe pearls today are grown too flat, due to the intrinsic characteristic of the host shell: Pinctada shells are usually flatter than Pteria shells (the shells being much more concave) which does not allow for the use of tall implants, since these will touch the opposite shell and will cause the...
      08-23-2021, 11:20 PM
    • Mabe Pearl Grading - 6) Nacre Quality
      by CortezPearls
      The most important factor here is nacre thickness. Many Mabe are cultured for short periods of time (4 months) to obtain the most perfect shape, but at the expense of their nacre thickness and durability. On the other hand, there are producers that grown them for too long (over 12 months) and end up having pearls that have thick nacre, but their shapes are not standardized, and they may display one or more of the surface imperfections we discussed in the previous paragraph. There is usually a middle...
      08-23-2021, 03:47 PM
    • Grading Mabe Pearls -5) Surface Quality
      by CortezPearls
      As with other pearls, surface quality is an important attribute: the cleaner the surface is, the more desirable the Mabe is and more valuable too. The usual surface imperfections found in these are:

      • Missing Nacre: whitish, bite shaped marks.
      • Spots, pinpricks: dark or light-colored pin-prick markings.
      • Rippled surface: these are markings caused by the growth of the abductor muscle on top of the blister pearl. This marking causes the appearance of wavy...
      08-23-2021, 03:30 PM
    • Grading Mabe Pearls - 4) Mabe Luster
      by CortezPearls
      Mabe pearls are not very known for their great luster, although many of these pearls may display amazing luster. Mabe usually display a more silky or subdued luster, especially in the Pinctada species and is most shiny in the Pteria species…but luster is usually enhanced by means of a final polishing, done with a high-speed cloth-wheel and a polishing compound, although much care must be taken to avoid excessive polishing that leads to heat and may ultimately damage the pearls by “burning”...
      08-23-2021, 03:26 PM
    • Grading Mabe Pearls - 3) Colors
      by CortezPearls
      Mabe pearl color is highly dependent on the species of mollusk that is producing the blisters, and even within each species you will be able to find a great variation of all-natural colors, but many Mabe are also dyed to produce an artificial coloration. Although we will not go in great detail on this subject, we will quickly cover some of the ways these pearls are given these artificial colors.

      We have already covered the different natural colorations we can find in the different species...
      08-23-2021, 03:22 PM
    • Grading Mabe Pearls - 2) Mabe Shapes
      by CortezPearls
      Mabe pearls can have any shape desired, as long as you attach it to the mollusk’s shell. Some cultured pearls have done this same thing, especially some freshwater pearls that have used faceted mother-of-pearl beads to produce so called “diamond pearls”, or star- and even shuriken- shaped pearls, but in the case of Mabe pearls it is even much varied and you can find hearts, stars, teardrops, ovals, crosses, and basically, any other possible combination you can think of as long...
      08-23-2021, 03:11 PM
    Working...
    X