Victorian freshwater pearls, before anyone had worked out how to farm them. Victorian Freshwater Pearl Earrings, 18K gold
Pearl vocabulary confuses buyers because it mixes three different questions into one word. Was it farmed or found? Which mollusc made it, and where? And what shape did it come out? A pearl described as "cultured freshwater baroque" has answered all three, and once you can read the three answers separately, pricing stops being mysterious.
Question one: natural or cultured
Natural pearls formed without human involvement, and before the 1920s every pearl in existence was one. They are genuinely rare, since the odds of finding one required opening enormous numbers of oysters, and this scarcity is why pearls were historically as valuable as diamonds. Antique jewelry made before roughly 1925 contains natural pearls by definition.
Cultured pearls are grown in farmed molluscs after a technician inserts a bead or piece of tissue to start the process. The nacre is real and grown by the animal; the trigger was human. Mikimoto perfected the method in Japan in the 1910s and 1920s, and it collapsed the price of pearls within a generation.
Imitation pearls are glass or plastic beads coated in a pearlescent finish, and the tooth test separates them from both of the above in a second, as described in how to tell if pearls are real.
Question two: which type
| Type | Source | Typical size | Character |
|---|---|---|---|
| Akoya | Saltwater, Japan and China | 6 to 9 mm | The classic round white pearl with sharp lustre |
| Freshwater | Lakes and rivers, mostly China | 4 to 12 mm | Softer lustre, wide colour range, usually solid nacre |
| South Sea | Australia, Indonesia, Philippines | 9 to 20 mm | Large, satiny, white to deep gold. The most expensive |
| Tahitian | French Polynesia | 8 to 16 mm | Naturally dark: grey, green, aubergine, peacock |
| Keshi | Any, a by-product | Small | All nacre, no bead, irregular, intense lustre |
| Mabe | Grown against the shell | 10 to 20 mm | Domed with a flat back, used in rings and earrings |
One correction worth making, because it costs people money: black pearls are usually not naturally black unless they are Tahitian. Dyed freshwater and Akoya pearls are sold as black constantly and honestly, and the price difference is very large. Dye tends to concentrate around the drill hole, which is where to look.
Question three: shape
Round is the rarest and most expensive in any type. Off round and button are near misses at a fraction of the price. Drop and pear suit earrings and pendants. Baroque is irregular and, in good nacre, often the most beautiful thing in the tray. Circle pearls carry natural rings around them.
Shape is a matter of taste and price rather than quality. A baroque South Sea pearl with superb lustre is a better object than a perfectly round freshwater with none.
Nacre in another form entirely, cut from the shell rather than grown as a bead. Sea Shell Pearl Charm Bracelet, 18K gold, 7.75 inches
What actually decides the price
Lustre first and always. Look at a light source reflected in the pearl: on a good pearl the reflection has a sharp edge, on a poor one it is soft and milky. Nothing else matters as much.
Nacre thickness. Bead-nucleated pearls have a shell bead inside, and a thin coat of nacre over it wears through, goes dull, and eventually shows the bead. Freshwater pearls are often solid nacre throughout, which is a genuine advantage.
Surface, meaning how few blemishes. Matching, on a strand, which is laborious and expensive. And size, which rises steeply because large pearls take years.
Living with them
Pearls are soft, porous and organic. Perfume, hairspray, sweat and acids all attack nacre, so the rule is jewelry on last and off first. Never use an ultrasonic cleaner or a chemical dip. Wipe with a soft damp cloth and dry at once. Restring strands every year or two if worn often, since old silk breaks without warning, and always with knots between the pearls so a break costs one pearl rather than fifty.
Frequently asked questions
What is the difference between natural and cultured pearls?
Natural pearls formed without human involvement and are rare; cultured pearls grew in a farmed mollusc after a technician started the process. The nacre in both is real.
Are antique pearls natural?
Pearls in jewelry made before roughly 1925 are natural, because cultured pearls were not yet in general commercial use.
Which pearls are most valuable?
South Sea pearls, for their size and satiny lustre, followed by fine Tahitian and top-grade Akoya. Lustre outranks type at any level.
Are freshwater pearls real pearls?
Yes. They are cultured in freshwater mussels and are often solid nacre throughout, which makes them more durable than thinly coated saltwater pearls.
Are black pearls naturally black?
Tahitian pearls are naturally dark. Most other black pearls are dyed, which is legitimate but far cheaper. Dye often shows around the drill hole.
What is a baroque pearl?
An irregularly shaped pearl. Baroque shapes cost less than round ones of equal quality, and in fine nacre they are frequently more interesting.
How often should pearls be restrung?
Every one to two years for frequently worn strands. Insist on knots between pearls so that a broken string does not scatter the whole necklace.
Read next: How to tell if pearls are real · What is mother of pearl? · How to store jewelry
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