In case I ever write the fine jewelry thriller (that is, a thriller about fine jewelry) that I have in mind, I signed up for a Zoom class on “gems,” taught by a registered gemologist. Now I really have to write that story! Our instructor, Hillary Spector, was fantastic, and here are some of the pearls I gleaned.

Diamonds

Diamonds form in the earth’s mantle, in the presence of intense heat and pressure, plus their constituent element, carbon. They were formed up to 3.3 billion years ago and carried up closer to earth’s surface through volcanic action as “recently” as 20 million years ago. They may be a girl’s best friend, but they are an old friend.

Diamonds are at the top of the scale in terms of hardness, but they can break or chip. The toughest stone used in jewelry is jade. Hardness and toughness aren’t the same.

Look for the four C’s when assessing a diamond: cut (the sparkle), color, clarity, and carat (how much it weighs, not how big it looks); these are all measurable attributes. If my fictional jewelry seller is pushing a stone’s beauty, that’s irrelevant to value and, therefore, the asking price, which depends on rarity.

Lab-grown “synthetic” diamonds are chemically and anatomically the same as a mined diamond. Sellers are required to make it clear to purchasers that the diamond was not mined (opportunities for fraud?).

Pearls

Pearl jewelry is having a renaissance, and pearls are even appearing in engagement rings (not a good idea; they are neither hard nor tough enough for daily wear). In London, I saw the unfortunately termed pearl choker of Mary Queen of Scots, which was so small it looked the size of a bracelet.

Forget the old distinction between “natural” and “cultured” pearls. All pearls on the market today are cultured. The commercial prospects for natural pearls have been lost to ocean pollution and global warming (increasing the temptation to steal vintage natural pearls?).

Once one or more mother-of-pearl beads is inserted into a pearl oyster, growers give the pearl at least ten months to form, but 24 months is optimal. All Akoya pearls are bleached and may be further colored with dye or irradiation. By law, this must be disclosed to the buyer, which opens up possibilities for scamming!

Freshwater pears form in freshwater mussels, primarily cultivated in China (international intrigue)!

The value of a pearl is always related to rarity. Like the four C’s of evaluating diamonds, the actors that rate pearls are measurable, independent, and must all be present: size, shape, color, luster (shine), surface quality, enough layers of nacre, and, if they are supposed to be “matching,” must match on all those characteristics. (“Their beauty justifies the ‘investment,’” says the deceptive salesperson.)

Must Re-watch!
Diamonds are Forever
The Hot Rock
Return of the Pink Panther
Girl with a Pearl Earring