shape and overall quality? An nice-quality, round, 8-mm natural-color black or gold pearl can retail for between $150 to $300. A round, 8-mm dyed pearl may retail for about $40 to $100. (Remember to compare pearls of the same size and shape. These factors have a major effect on the price. For example, if we just decreased the size of the dyed pearl to 6 mm, it could retail for about $20.)

True black pearls are typically expensive, so if the price is low and you're not in Tahiti, assume the pearl is dyed unless otherwise told. (It's illegal to import or sell dyed black pearls in Tahiti.) Keep in mind, however, that good quality dyed pearls are not cheap.

Dyed golden pearls can be sold anywhere so always ask if the color is natural. If the store claims the color is natural, ask if they will write this on the receipt.

Size Test:   Is the size less than 8 mm? If so, and you are not in Tahiti, assume that it is an Akoya dyed pearl or an Akoya "blue pearl" (a dark colored pearl which derives its color from foreign contaminants in the nacre itself or between the nacre and the shell bead nucleus). There are true black Tahitian pearls less than 8 nun, but it is usually not cost effective to intentionally produce them when farmers can get far more by cultivating larger pearls. If a dark pearl is of natural color, the store should be willing to write this on the receipt. Akoya oysters, on the other hand, can produce a wide range of pearls below 9 mm; but rarely do they grow round pearls above 10 mm. Larger Japanese bar­oque pearls may be available. A photo of some Japanese "blue pearls" ranging from 11.5-14 mm can be seen in the fall 1990 issue of Gems & Gemology.

Once in a while, large round pearls from South Sea oysters are dyed or are "blue pearls. " Therefore large size is never proof that a pearl is a true black pearl. It is, however, a positive sign. When buying black pearls, it's advisable to ask salespeople to specify on the receipt that the pearls are of natural color. When spending large sums of money, also have them tested by an independent gem lab.

Drill-hole Test  If it's possible to look into the drill hole with a loupe, does the nacre inside look white and the nucleus look dark? This is a sign the pearl has been colored by irradiation or the nucleus has been dyed. Is there dye concentrated around the drill hole? This indicates it's dyed. Sometimes undrilled dyed golden pearls have pits or cracks which allow you to see a dark nucleus.

Color Test   Are the pearls so dark they're almost black or so yellow they look fake? Do all the pearls in the piece look the exact same color? Is the color per­fectly even in all the pearls? Do the yellow or gold pearls look grayish? These are indications the pearls might be dyed. It's not easy to find several black or yellow pearls the exact same even color. Neither is it easy to find true black pearls that are really black. More often than not they are grayish.

If you're interested in black pearls, look at a lot of them. Then look at dyed pearls and compare. Gradually, you'll get a sense of what the body colors and overtones of black pearls look like. People who work with black or yellow pearls on a regular basis can usually spot dyed pearls instantly. But even experts can be fooled. So when making a major purchase, have your pearls tested by an independent gem lab.

If you're interested in black pearls, look at a lot of them. Then look at dyed pearls and compare. Gradually, you'll get a sense of what the body colors and overtones of black