Black cultured pearls are ‘grown’ in Polynesian waters and come from the black-lipped Pinctada Margaritifera species of pearl oyster specifically cultivated in the many lagoons of French Polynesia.
Although they are called black, the colors are quite diverse and can range from light gray to a dark gray to the more well known black. There are also blue and green and even pink overtones available although these are rare and quote costly.
Specifically in French Polynesian the term, “Tahiti Cultured Pearl” is reserved exclusively for cultured pearls obtained from the grafting of the locally cultivated Pinctada Margaritifera pearl oyster. These pearls have a continuous pearly layer of at least 80% of their surface and do not reveal either the nucleus or the seed of the nucleus. Any other pearl that does not satisfy this criteria may not be called a “Tahiti Cultured Pearl” and will be considered a rejected pearl.
To be a rejected pearl includes those pearls with over 20 percent of their surface having a milky loss of pigmentation and have no or little luster resulting in a dull surface. It also includes pearls with imperfections on more than half of it’s surface. Only the highest quality Tahitian cultivated pearls are accepted as bona fide Polynesian pearls.
Of course an important part of pearl maintenance is how to look after pearls. The pearl is produced by a living organism and are therefore sensitive to chemicals and acids. Although pearls are meant to be worn it is important to ‘rest’ them sometimes and store them away from light and give them time to ‘recover’.
Do not clean them in solvents, detergents or other chemicals. Do not use ultrasonic cleaners or steam clean them. Both methods will damage pearls beyond repair.
Pearls should be washed in plain or salty water to remove skin chemicals and acids which can east into the pearl and contribute to it losing its shape. They should be dampened from time to time in a warm lightly salted water and stored separately from other jewelery so they are not scratched by gemstones. Also do not wrap them in cotton wool or other substances as the heat generated can dry them out, create cracks and even turn them brown over time.
Olive oil is good to help them preserve their luster when storing them away for long periods of time. Pearls are soft, unlike gemstones, and must be treated with care.
Provided you look after you black cultured pearls, they should last you a lifetime.