How to choose the best
Rub two pearls together; if they feel smooth and not gritty, they may be fake. Look at pearls on a white surface under natural light and examine their size, luster, imperfection, and orient the technical term for the kind of iridescence found in the best pearls. Fluorescent lights are bad for judging pearls.
Perfectly round pearls are the most valuable. Roll a strand on a smooth surface to see if any pearl wobbles. Brown pearls are a craze in the international market this year, but this may be just a fad; most brown pearls are dyed.
Avoid getting creamy, off-white pearls for elderly women, as they can accentuate yellowing teeth.
Tear-drop pearls are ideal for earrings and pendants. Baroque, or irregular shaped, pearls are the closest to nature but few people appreciate their aesthetic value.
The Chinese idiom "renlao zhuhuang" people grow old like pearls become yellow incorporates a common misunderstanding. With careful maintenance, precious pearls can remain shiny and retain their original color for centuries.
Don't store pearls with other jewelry or any hard objects. Take them out at least once a month and moisten them with a clean soft cloth. Never touch up pearls with perfume or other cosmetics. After wearing them, clean them again gently with a moist cloth.
China Daily
(China Daily 03/30/2007 page19)