Single strand Tahitian gray pearl necklace with a two-leaf silver clasp

How it is made

The words of the trade, one by one, explained to those who do not know them.

01

Tahitian pearl

The pearl is the only gem produced by a living animal. It is nacre, not a crystal grown in rock. The oyster lays it down in very thin layers around a nucleus, one on top of another for years, and the light you see on the surface is the sum of those layers. The gray of Tahitians is theirs by birth: it comes from Pinctada margaritifera, the black-lipped oyster, and it is not a dye. But nacre is soft: it scratches with a fingernail, and perfume, hairspray, vinegar and sweat corrode the surface until the sheen goes out. It is put away dry, and never shut in a bag where no air passes.

02

Pearl

The pearl is the only gem produced by a living animal, and it does not have the nature of the other minerals. It is made of aragonite — calcium carbonate — held together by conchiolin, an organic substance the mollusc lays down between one layer and the next. That organic part is its weak point. On the hardness scale a pearl sits around three: it scratches with a fingernail, and the metal of another piece of jewelry marks it at the first contact. But the scratch is not the worst damage: being a carbonate it dissolves in acids, and sweat, perfume, hairspray and vinegar corrode the surface until the sheen goes out. It goes on last, after the perfume, and comes off first; it is cleaned with a barely damp cloth and put away dry, never shut in a bag where no air passes. And the thread or cord that holds it is watched too: it is the part that ages first, and it should be replaced before it gives, not after.

03

Hand stringing

The stones are threaded one at a time, and the thread that holds them has to carry the weight of them all. The holes never fall exactly at the center of the bead: whoever strings decides which side to enter from, because a bead turned the wrong way makes a step and the thread hangs crooked. The last operation is the knot, and it has to be closed with the thread already under tension: a little slack and the necklace bellies, a little tight and it stops falling.

04

Composing the strand

The pearls of a strand do not come out of the oyster alike: they change by a tenth of a millimeter at a time, and they change in sheen. Composing a strand means first discarding — keeping only the ones that belong together in color and luster — and then setting them in the right order, the largest at the center and the smallest towards the ends, because with the naked eye a step in size shows before a difference in color. It is work done once only: changing the order afterwards means undoing the whole strand and starting again.