It's still June, so that means: It's still Pearl Time!
There are thousands of varieties of mollusks in the world, but only 20 varieties can produce a pearl. This week, let’s look at the main pearl varieties on the market today along with some of their distinguishing features.
The Akoya was the first pearl variety successfully cultured by Mikimoto. As a result, the variety is largely associated with Japan and is considered the “classic” pearl look--it is small, white and has subtle rosé overtones. Largely due to the cold waters in which they are grown, Akoyas have the highest luster of any pearl variety. Cold temperatures cause the oysters to slowly produce nacre, resulting in tightly packed layers that give a mirror-like reflective quality. Akoyas take 8 months to 2 years to form.
Cultured freshwater pearls are cultivated in mollusks in freshwater lakes and ponds. They come in the widest range of sizes, shapes and naturally occurring colors including white, cream, yellow, pink and a range of pastels. Freshwater pearls are typically cultivated without using a bead-nucleus, creating a pearl that is made entirely of nacre.
Pearls are so prevalent on the market today largely as a result of the influx of freshwater pearls from increased growing in China. With a culturing time of 18 months to 5 years, a single mollusk can produce up to 40 pearls in a single harvest if it is seeded with multiple pieces of tissue. Each mollusk can produce a harvest of up to 40 times 2-3 times in a lifetime. The resulting abundance of freshwater pearls has lead to an increasingly affordable price of pearls.
South Sea Golden and South Sea White Pearls
Beloved for their large size and high satin-like luster, South Sea pearls are one of the rarest varieties pearls. The name “South Sea” was given to differentiate Akoya pearls of Japan from those grown in areas surrounding and including the Indian Ocean. The South Sea pearl is grown one at a time in largest pearl bearing mollusk, the Pinctada maxima, in two varieties: silver-lipped and golden-lipped. The varieties describe the color of the inside edge of the shell, which indicates (along with the color of the donor tissue mollusk) the color of the harvested pearl.
Because the South Sea oyster very rarely breeds in captivity, 80-90% of the oysters the produce South Sea pearls are retrieved from the wild before being implanted to produce a cultured pearl. This adds to the rarity of the pearl variety, as does the sensitivity of the oyster. The South Sea oyster lives in pristine water, far from industrial pollutants. With warmer water temperatures, the oyster produces nacre at a rapid rate. With a culturing period of 20 to 24 months, the nacre grows to between 2-6mm. This is a very thick layer of nacre, especially when compared to the 0.5mm nacre thickness of an average Akoya pearl!
If the oyster produces a pearl of good quality it will be nucleated again, with a slightly larger bead. The process can be repeated up to three times, and a progressively larger bead is implanted during each process.
Confusingly enough, the Tahitian Pearl is not necessarily grown in Tahiti! Over the course of 22-26 months, Tahitian Pearls grow in many of the 130 islands that make up French Polynesia and the Cook Islands.
Tahitian pearls are prized for their wide range of colors including black, gray, green, blue, and brown with approximately 26 different overtones and often a naturally occurring metallic sheen. The body color of the Tahitian pearl is caused by nutrients present in the water, environmental conditions, as well as the DNA of the donor tissue. The three finest colors of Tahitian pearls are considered to be:
Peacock: dark green gray to blue gray with rosé to purple overtone.
Aubergine: dark grayish purple (aubergine is the French word for "eggplant.")
Pistachio: yellowish green to greenish yellow
Now that we have established the main varieties, let’s talk about pearls getting funky!
Keshi pearls are some of my favorite and can come from any and all varieties of pearl. The name ‘keshi’, meaning poppy seed in Japanese, refers to the way in which the pearls form as a by-product of the culturing process. Occasionally the mollusk will reject the bead nucleus during the culturing process. If left uncorrected by the pearl farm, the mollusk will continue to secrete nacre and produce a pearl without a bead nucleus, forming a keshi pearl. A keshi pearl may also form when cells from the implanted mantle tissue separate from the implanted bead and continue the nacre secreting process in the pearl sac. Keshi are usually baroque in shape. I love their unpredictability!
Mabé pearls are pearls that are assembled by a person. With mabé pearls, a nucleus is attached to the inside of the mollusk’s shell with a piece of mantle tissue. Nacre forms over the nucleus, holding the pearl to the shell. The harvesting process kills the mollusk because the pearl is cut off of the shell. The nucleus is then removed and the cavity is filled with a polymer and a backing is attached—sometimes this can another mabé, creating a double dome shape, other times the backing is shell or plastic. Because they are assembled, mabé pearls are more delicate than other pearl types.
I hope, after four weeks of my gushing about the beauty, intricacies, and details (I know, I know! Lots of information!) of pearls, you see them in a new lustrous light.
Before we sign off and enter July, ruby red month, take a minute to read about how to care for your freshly-loved pearl collection below!
• Have strands cleaned and re-strung annually if worn regularly. • Avoid sudden temperature changes. • Avoid contact with cosmetics, hairspray, perfume, or household chemicals. • Do not use ultrasonic cleaning to clean your pearls • Avoid over exposure to bright light