Rub the pearl gently against the edge of your front tooth. Real pearls — natural or cultured — feel slightly gritty, like very fine sand; imitation pearls feel glassy smooth. That single test takes ten seconds and catches most fakes. Weight, warmth and the drill hole confirm the verdict in the remaining fifty.

We still tooth-test at the sorting table out of pure habit, decades after we stopped needing to. It works because it reads the material itself, not the packaging or the sales pitch — and the material is the one thing a fake can’t copy.

Start with the tooth test

Real pearl nacre is built from microscopic platelets of aragonite — a crystal form of calcium carbonate — stacked like brickwork in thousands of layers. Those layer edges are what your tooth feels: a fine, dry grit, something like chalk dust on glass. Imitation pearls are glass or plastic beads wrapped in lacquer, and lacquer is dead smooth.

Do it properly: wipe the pearl clean, touch it to the biting edge of a front tooth, and slide it sideways with almost no pressure. You’re feeling, not biting. Done gently, it leaves no mark on a real pearl and tells you nothing less than the truth. If teeth aren’t an option — at a counter, say — rubbing two pearls softly against each other gives the same answer: real nacre grips slightly, lacquer skates.

Four more checks before the minute is up

• Temperature. A real pearl feels cool the moment it touches skin, then warms slowly. Plastic fakes are warm from the first second.
• Weight. Solid nacre has heft. Plastic imitations feel toy-light in the palm; glass fakes pass this one, which is why no single test is enough.
• The drill hole. Under any magnifier, a real pearl shows a crisp hole and, often, visible nacre layering inside. Imitations show chipped or peeling coating around the rim, like old paint at a screw.
• Strand variation. Real pearls are grown, so neighbours differ a touch in size, tone and surface. A strand of perfectly identical, flawless spheres is a strand of mouldings.

The sixty-second routine

Here’s the whole screen, in the order we’d run it on a counter:

Two or more failures and you can stop being polite about it. One caution in the other direction: a single passed test proves little, because good glass fakes are cool and heavy too. It’s the pattern across all five checks that convicts or acquits.

What counts as a “real” pearl

Cultured pearls are real pearls — that’s not marketing, it’s the official position of CIBJO, the world jewellery confederation. A technician starts the process; the oyster grows the pearl from the same nacre a wild pearl has. Akoya (Pinctada fucata), South Sea (Pinctada maxima) and Tahitian (Pinctada margaritifera) pearls are all real cultured saltwater pearls. “Imitation” means no oyster was involved at all: glass, plastic or shell beads dressed in pearlescent coating.

Dark pearls deserve one extra step, because imitation isn’t the only trick — treated colour is. We cover that separately in how to tell if a Tahitian pearl is real.

Does the tooth test damage pearls?

Not when it’s done gently — a light sideways slide against the edge of a tooth, never a bite. Nacre is harder than the test gives it credit for; we’ve tooth-tested thousands of pearls that went on to grade flawless.

What are imitation pearls made of?

Most are glass or plastic beads coated in a pearlescent lacquer, sometimes one containing fish-scale essence. Shell-based beads turn up too, marketed under names like “shell pearls”. The better ones look convincing in photos; almost none survive the tooth test plus a loupe on the drill hole.

When should you pay for a lab test?

When real money is involved and the question isn’t real-versus-fake but cultured-versus-natural or treated-versus-untreated colour. An x-ray shows the internal structure in minutes — the same principle we use when x-ray sorting harvests at the farm.

The fastest education, though, is holding the real thing. Pick up a strand from our Akoya pearls or a single pearl from our loose Tahitian pearls, run the sixty seconds yourself, and you’ll never be fooled at a market stall again.