An Exceptional Conch Pearl Ring

Article from Berganza


Tuesday 14th September 2010

Conch— pronounced 'conk'—pearls come from the Queen conch mollusk, which lives primarily in the Caribbean Sea. Conch pearls are typically thought of as pink, though they can also occur in orange, yellow, brown, white, and purple hues. They are one of the rarest types of pearls, with about one out of every ten thousand conchs containing a pearl, approximately twenty percent of which are gem quality. They are becoming increasingly uncommon due to the overharvesting of conchs, which has resulted in the banning of conch fishing in the majority of the countries that border the waters in which they make their habitat.

All mollusks have the ability to produce pearls, which fall into one of two categories—either nacreous or non-nacreous.  Nacreous mollusks, as the name suggests, have the ability to produce 'nacre', more commonly known as mother-of-pearl, a lustrous and often iridescent substance. Non-nacreous mollusks, on the other hand, produce a non-lustrous material which, in the most desirable circumstances, displays a porcelain-like surface and sometimes a highly desired, flame-like structure termed 'chatoyancy' (or the cat's eye effect) below the surface.  These are also sometimes called 'calcareous concretions', because it is debated as to whether or not they should even be categorized as pearls, which according to some are defined as being composed of nacre.  Both types are similar in chemical make-up—a composite of the mineral aragonite (calcium carbonate) and the protein conchiolin—however, they differ in structure. In nacreous pearls aragonite is arranged in sheets which are bound with conchiolin, whereas in non-nacreous pearls aragonite forms in needle-like crystals with a smaller percentage of conchiolin.  Conch pearls are non-nacreous, but are always porcellaneous and often chatoyant.

One reason conch pearls, in particular, are so rare is due to the class of mollusck from which they derive.  Most pearls—including the traditional small, white nacreous Akoya pearls and the larger, colorful nacreous South Seas pearls—are formed in bivalve molluscks, composed of two hinged shells, such as oysters, mussels, and clams. Some pearls, however, form in gastropod molluscks, which are generally characterized by their spiralled, many-chambered shell. All pearls form as the result of an irritant, or a foreign particle trapped within the mollusk, around which the mineral/protein composite—either nacreous or non-nacreous—can form.  Therefore, because of their closed structure, shelled gastropods are much less likely to become imbedded with an irritant.  Furthermore, this characteristic contributes to the rarity of conch pearls, as it has thus far proved impossible to culture them, as is done with many nacreous pearls such as the Akoya (a process pioneered by the famed Mikimoto K?kichi in 1916), into which a shell 'seed', which acts as the irritant, is implanted, around which nacre forms. That said, in late 2009 two scientists at Florida Atlantic University's Harbor Branch Oceanographic Institute announced success in culturing conch pearls, examples of which are presently being studied by the Gemological Institute of America. Regardless, natural pearls are the most highly prized and will continue to be so.

Conch pearls first emerged as a recognizable jewelry trend in the 1830's. Their popularity peaked, however, in the early twentieth century, when the pink variety of the gem was found to integrate well with the fashion for delicate, diamond and platinum designs of that period, as seen in the present ring. In this way they were often used as stylized rosebuds or berries set within pavé diamond leaves. The American firm of Tiffany & Co. in particular promoted the gem, along with other gemstones from the Americas, in a nationalistic effort to legitimize the jewelry of the New World versus that of Old Europe. Despite their increasing rarity, conch pearls have been making a comeback in the past few decades, with famous wearers including Elizabeth Taylor and Jennifer Aniston.

REFERENCES

David Federman, The Pink Pearl:  A Natural Treasure of the Caribbean, Milan:  Skira Editore S.p.A., 2007.

Gem Reference Guide, Carlsbad, CA:  The Gemological Institute of America, 1995.

Neil Landman, et al, Pearls:  A Natural History, New York:  Harry N. Abrams, Inc., 2001.

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