How to buy pearls
Most people judge a pearl by how round it is. That is close to the least important thing about it.
Luster is everything
Luster is the quality of light returning from the surface of a pearl, and it is the single best indicator of quality. A pearl with excellent luster reflects sharp, bright, almost mirror-like images. A poor one has a soft, chalky glow with no definition.
This is a function of nacre — the thousands of microscopic layers of aragonite the mollusc lays down. Thick, well-formed, evenly deposited nacre produces depth. A thin coating over a large bead nucleus produces something that looks acceptable in a shop window and dull within a year.
Hold a pearl up and look for the reflection of a light source. If you can see its shape clearly, the luster is good.
Nacre thickness
Cultured pearls are grown around an implanted nucleus, and the amount of nacre laid over it depends on how long the pearl stayed in the mollusc. Longer cultivation means thicker nacre, better luster and a pearl that will still be beautiful in fifty years.
Thin nacre can eventually wear through or peel, particularly around the drill hole. A pearl where you can see a faint banding or the bead showing through is one to walk away from.
The families
- Tahitian — grown in the black-lipped oyster in French Polynesia. Naturally dark, in greys, greens, aubergines and peacock overtones. Fine ones are not dyed.
- South Sea — the largest cultured pearls, from Australia, Indonesia and the Philippines, in white, silver and gold.
- Akoya — the classic small round white pearl from Japan and China, known for high luster.
- Freshwater — mostly from China, now reaching remarkable size and shape variety, including the baroque forms that make the most interesting jewelry.
Shape, and why roundness is overrated
A perfectly round pearl is difficult to grow and priced accordingly. But roundness is a manufacturing achievement, not an aesthetic one, and an interchangeable sphere is exactly that — interchangeable.
Baroque and off-round pearls have character, and they let a designer build a piece around a specific shape. Some of the most interesting pearl jewelry being made uses shapes that a strict quality grader would mark down.
Matching
For a strand or a pair of earrings, matching is a large part of the value and almost all of the labor. Two pearls that look identical in a tray can read as clearly different once they are on either side of a face.
This is one of the reasons Sharon buys pearls loose and matches pairs by hand, in the light they will actually be worn in. No supplier does it as carefully as the person who has to set them.
Living with pearls
Pearls are soft — 2.5 to 4.5 on the Mohs scale — and porous. Put them on after perfume, hairspray and lotion, not before. Wipe them with a soft damp cloth after wearing. Store them away from harder stones that will scratch them, and never put them in an ultrasonic cleaner or a commercial jewelry dip.
A strand worn regularly should be restrung every few years. Silk stretches and eventually fails, usually at the worst moment.
Frequently asked
What is the most important factor in pearl quality?
Luster, which reflects nacre quality and thickness. A pearl with excellent luster reflects sharp, bright images; a poor one looks chalky. It matters more than shape or size.
Are Tahitian pearls naturally black?
Fine Tahitian pearls get their dark color naturally from the black-lipped oyster that grows them. Dyed pearls exist in the market and should be disclosed.
How should I care for pearls?
Put them on last, after cosmetics and perfume. Wipe with a soft damp cloth after wearing, store separately from harder stones, and never use ultrasonic cleaners or chemical dips.
