Get to Know Your Pearls

Traditionally, pearls are June’s birthstone, a title they vie for with other equally beautiful but less well known stones. Unlike every other birthstone I have written about here, pearls are not exactly stones. Pearls are made of calcium carbonate, like most hard objects in the ocean created by organisms. Oh, yeah, that’s the big unique pearl characteristic – they are made by animals.

Technically (and oh boy, do I love to get technical), pearls can be made by any shelled mollusks, though generally speaking, most of those pearls are just weird little curios and not pricey gemstones. The pearl oyster and the pearl mollusk are the dudes you want to talk to if you want to get into the gemstone business. Both freshwater and saltwater mollusks can get the job done, but since the beauty of the pearl lies in its nacre (that shimmery shiny sheen), you want to be sure you have the right bivalve.

Tahitian pearls, mostly a silvery-gray color though a few are yellow-ish or greenish.
Tahitian pearls. Photo taken by Remi Jouan, found in wikicommons.

Pearls are formed when an irritant, like a grain of sand, makes its way into the mollusk. The animal then starts to coat this irritant in layer after concentric layer of calcium carbonate. If only I could take all the things that cause me grief and turn them into beautiful and valuable gemstones. But I do not envy these mollusks too much – wild pearls, as opposed to cultured pearls, are exceptionally rare and many, many mollusks are killed in pursuit of them. I also do not envy the pearl divers who were usually people exploited by colonial powers. Gems: they basically all have a messy, ugly history.

But hunting for the perfect wild pearl was not an efficient business strategy: the few strands of completely wild pearls are valued in the hundreds of thousands of dollars, they are so rare.  Given the demand for the pearls, people began to cultivate pearls in the early 1900s. These cultured pearls are still created by mollusks, but the mollusks were helped along by people, either through implanting or grafting a starter pearl into a mollusk’s mantle or gonads. The pearls are harvested after the mollusk has had some time to secrete that lovely coating, usually 6 months to a couple of years depending on the pearl type. Akoya pearls are one of the best known cultured pearls.

Cultured and natural pearls can be determined by using x-rays since the pattern of secretion/layers of nacre differ between the two types. Only the natural wild pearls have those signature concentric rings. Generally speaking, the more rings a pearl has, meaning that generally speaking, the older a pearl is, the better its luster and color will be. These are the pearls that bring in the big bucks. The bigger the better in the pearl world, and not just because bigger is better in general but because the color will be that much nicer.

So if you’re buying pearls, chances are good you’ll buy a cultured one. Natural, wild pearls are rare and hugely expensive, and there are some lovely cultured pearls out there anyway. Look for ones with good luster and color, and if you can, read up a little on the process of pearl creation – not all cultured pearls are created equally.

Oh, and one last bit of advice: keep your pearls way the far away from vinegar and anything else acidic, I mean, unless you prefer your pearls dissolved.

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