A real Tahitian pearl feels faintly gritty against the edge of your tooth, never glassy like a glass or plastic bead. Genuine pearls also show tiny surface irregularities, sit cool and heavy in the hand, and glow with depth rather than a painted-on shine. Seven simple checks will confirm it almost every time.

We handle thousands of pearls a season on our sorting table, and the fakes give themselves away fast. You don't need a laboratory or a chemistry kit. You need your own senses, a jeweller's loupe, and a few unhurried minutes. Below are the same checks our graders run before a pearl ever earns a place on a strand.

The seven tests we use at the sorting table

When a parcel crosses our bench in French Polynesia, we work through these one by one. None of them needs a lab, and every one of them is non-destructive when you go gently.

Why the tooth test works

Real nacre is built from thousands of microscopic aragonite platelets, laid down tile by tile by the black-lipped oyster, Pinctada margaritifera. Those overlapping layers create a texture your enamel can feel. A glass or resin bead is moulded perfectly smooth, so it glides. Rub lightly across the surface — you're reading texture, not trying to scratch anything. Two seconds tells you a lot.

Read the drill hole and the overtone

The drill hole is the most honest part of any pearl. On a genuine Tahitian you can often see thin concentric nacre layers around the bore, like the growth rings of a tree; on a fake you'll see a chipped coating or a hollow plastic core. Then tilt the pearl in daylight. A true Tahitian is naturally grey to black, and a real Tahitian shows shifting peacock, green and aubergine overtones that travel as the light moves — colours grown by the oyster and never dyed onto the surface.

What a certificate proves, and what it doesn't

An honest seller will tell you the pearl is a cultured Tahitian, name the species, and disclose the grade on the common producer scale (AAA, AA, A). That AAA–A scale is set by farms and dealers — a trade shorthand, not a GIA grade. GIA grades pearls on its own seven-factor system instead, so the two should never be fused into a phrase like "AAA certified by GIA". What you really want is plain honesty about the fact that the pearl is cultured.

Red flags that should give you pause

• A price that seems too good for an 11mm round black pearl — the harvest maths rarely allows it.
• A whole strand described as "perfectly round and flawless"; nature varies, and we sort accordingly.
• Colour that looks flat and printed rather than shifting as you rotate the pearl.
• A seller who calls a pearl "genuine" but won't say whether it is natural or cultured.

Are all black pearls real Tahitians?

No. Many cheap "black pearls" are colour-treated freshwater imitations or coated glass beads — something we never do, because our Tahitians are not dyed. A real Tahitian (Pinctada margaritifera) earns its dark body colour naturally inside the oyster.

Can I test a pearl without damaging it?

Yes. The tooth, weight, temperature and loupe checks are all gentle and reversible. Skip anything that involves heat, acid or a blade — you don't need them, and they can ruin a genuine pearl.

Should I worry about small surface marks?

Quite the opposite. A few tiny natural marks are reassurance that the pearl grew inside a living oyster rather than a mould. We grade for clean surfaces, but we never pretend nature is perfect.

Want to handle the real thing? Browse our loose Tahitian pearls and feel the weight for yourself, or read what makes a Tahitian pearl valuable before you compare two pearls side by side.