How to Tell If Pearls Are Real: 6 Tests That Work and 4 That Don’t

Most imitation pearls are a glass, plastic or shell bead under a shiny coating, and the coating is what gives them away. It feels smooth where real nacre feels gritty, and it frays at the drill hole where nacre ends in a clean edge. Your teeth and a 10× loupe will sort most strands in a couple of minutes. What no home test can do is tell a natural pearl from a cultured one — and both are real pearls.

First, what “real” means

There are three kinds of pearl-like bead, and the rules name each one. A natural pearl forms inside a mollusk with no human help. A cultured pearl forms the same way around a nucleus — usually a bead of shell — that a farmer plants inside the mollusk, which then coats it in nacre. It is made of the same material as a natural pearl and it is a real pearl. An imitation is a manufactured bead made to look like one, and it isn’t a pearl at all.

In the United States the FTC’s Jewelry Guides keep the word “pearl” on its own for natural pearls. A cultured pearl has to be sold as “cultured” or “cultivated”, and an imitation as “imitation”, “simulated” or “artificial”, with the qualifier as prominent as the word pearl. The same goes for “faux pearl” and “fashion pearl”, and an imitation may not be called “real” or “genuine”. GIA says the vast majority of pearls on the market are cultured, so the question a home test can answer is nacre or coating? — not natural or cultured.

The tests, from harmless to definitive

1. Look along the whole strand

Pearls grow, so even a well-matched strand shows small differences in size, shape, colour and surface. GIA counts how closely the pearls match as one of its seven value factors, which tells you perfect sameness is the exception. Lay the strand on a white cloth and roll it slowly under a good light. Slight variation and the odd tiny blemish are what nacre looks like. Beads that are identical in every way are a reason to look harder at the next tests, not proof of a fake — the best cultured strands are matched very closely too.

2. The tooth test

Rub the pearl gently along the cutting edge of your front teeth. Nacre is built of microscopic platelets of aragonite, a form of calcium carbonate, each 10 to 20 micrometres across, and their edges catch. Natural and cultured pearls feel slightly gritty, like very fine sandpaper; glass and plastic imitations feel glassy smooth. GIA described exactly this in its 1990 study of Majorica imitations — cultured pearls gritty, Majorica smooth — with two warnings. The test can wear the pearl, so press lightly and use one near the clasp. And some manufacturers make imitations with a gritty surface, so grit on its own doesn’t prove nacre. Smooth, on the other hand, is a strong sign of an imitation.

3. Rub two pearls together

The same test without your teeth: rub two pearls from the strand gently against each other. Real pearls feel slightly gritty; imitations glide completely smooth. It has the same limits as the tooth test and the same risk of wear, so do it once, lightly, with pearls from the back of the strand.

4. Look into the drill hole

This is the best home test. Use a 10× loupe, or a phone camera zoomed in, and look at the edge of the hole where the string goes in. On a cultured pearl the edge is sharp and well defined, and you may see a thin dark line where the nacre meets the shell bead in the middle. On a coated imitation the edge looks ragged: GIA found the coating frayed at the hole on Majorica beads, and chipped and peeling — with white shell showing underneath — around the holes of shell-bead imitations. A coating that has flaked anywhere, showing a different material underneath, settles it.

5. The surface under a loupe

In good light at 10×, nacre isn’t perfectly smooth. Its platelets grow in fine, wavy ridges that GIA compares to fingerprints or a topographic map. If you can see that pattern, you are looking at nacre. If you can’t, it proves little — on a polished pearl the lines can be too fine for a loupe — so go back to the drill hole. At 50× in GIA’s study, cultured pearls showed small step-like ridges and Majorica beads a pitted, dimpled texture.

6. A lab report — natural or cultured

The only way to know whether a real pearl is natural or cultured is to see inside it. Gem labs use X-rays: GIA calls microradiography the most reliable non-destructive way to see a pearl’s internal structure. A beaded cultured pearl shows a solid centre with no growth rings around it; a natural pearl shows concentric growth rings. If a strand is offered as natural, ask for the lab report before you pay a natural-pearl price — and get one before you insure or sell a strand you believe is natural.

Four “tests” that prove nothing

• The vinegar test. Pearls are calcium carbonate, and GIA warns that all acids damage them — even perfume, hair spray and sweat. A drop of vinegar can only etch a real pearl; it can’t tell you anything the drill hole won’t show safely. GIA calls the laboratory’s own acid test highly destructive and doesn’t recommend it.
• The lighter test. GIA says high heat can burn pearls or make them discolour, split or crack. Whatever a flame shows you, it shows by damaging the pearl.
• Weight and temperature in your hand. GIA found Majorica beads overlap cultured pearls in specific gravity, and shell imitations have a similar heft, so a strand that feels heavy proves nothing. Neither does a pearl that feels cool against the skin: glass feels cool too.
• Knots between the pearls. Knotting is careful stringing, not a certificate. GIA explains it as protection — if the string breaks you lose one pearl, not the strand, and the pearls don’t rub against each other. Imitation strands can be knotted too.

Which kind of pearl is it?

Once you know the pearls are real, the type shapes what they are worth. GIA gives these typical sizes for the four main cultured pearls, and notes that every type can fall outside them:

• Akoya — usually under 9 mm; mostly from Japan and China.
• Tahitian — 8 to 14 mm; from French Polynesia.
• South Sea — the largest, 8 to 18 mm; from Australia, Indonesia and the Philippines.
• Freshwater — most often smaller, near-round or oval; China is the leading source.

Freshwater pearls are real pearls too, and every test above applies to them. If the pearl is set in a ring, our guide to identifying the stone in a ring covers what else might be sitting in the setting.

Putting the results together

• Gritty, a sharp clean drill hole, small differences along the strand — real pearls, natural or cultured. Only a lab report says which.
• Smooth on the teeth, a ragged or peeling drill hole — an imitation. What it’s worth is the design and the clasp, not the pearls.
• Gritty, but a flaking coating somewhere — an imitation with a textured coating. Trust the drill hole over the grit.
• Sold as “natural” — ask for the lab report. Under the FTC Guides, cultured and imitation pearls may not be called natural.
• A stamped clasp — 14K, 585, 750 or 925 tells you about the clasp, not the pearls. Our gold and silver guides show how to test it.

Do first

The tooth test, then the drill hole under a loupe

Rules it out

A glassy smooth feel; a ragged, chipped or peeling coating at the hole

Rules it in

Gritty nacre and a sharp, clean drill hole — natural or cultured

Natural or cultured

Only a lab X-ray

Pearl numbers

Platelets 10–20 µm · specific gravity 2.60–2.85 · 7 GIA value factors

Skip

Vinegar, a lighter, weighing in your hand, and knots

The takeaway

Real or fake is a two-minute job: your teeth, then a loupe on the drill hole. Natural or cultured is a lab’s job, and it is the question that moves the price. If a strand passes the home tests, GIA’s seven value factors — size, shape, colour, lustre, surface, nacre quality and matching — are what a jeweler will look at next. If you are sorting a whole jewelry box, our guide to real versus costume jewelry covers the rest of the pile, and what is my ring worth explains how a verified piece turns into an offer.

At a glance

Pearl tests compared

Test	What it tells you	Risk to the pearl
Look along the strand	Small differences are normal in real pearls; perfect sameness is a reason to look closer	None
Tooth test	Gritty points to nacre, smooth to an imitation — but some imitations are made gritty	Light wear if pressed hard
Rub two pearls together	The same as the tooth test	Light wear
Drill hole under a 10× loupe	A sharp, clean edge is nacre; a ragged, chipped or peeling coating is an imitation	None
Surface under a loupe	Fine, wavy growth lines like a fingerprint are nacre	None
Lab X-ray	Natural or cultured, and what is inside	None
Vinegar, a lighter	Nothing a safe test won’t — they work by damaging the pearl	High

Frequently asked questions

Are cultured pearls real pearls?

Yes. A cultured pearl grows inside a mollusk around a nucleus — usually a bead of shell — that a farmer plants there, and the mollusk coats it in the same nacre as a natural pearl. In the United States it must be sold as “cultured” or “cultivated”; the word “pearl” on its own is kept for natural pearls. According to GIA, the vast majority of pearls on the market are cultured.

Does the tooth test really work?

Mostly. Nacre is built of microscopic platelets, so natural and cultured pearls feel slightly gritty against the edge of your teeth, while glass and plastic imitations feel smooth. GIA notes two limits: some imitations are made with a gritty surface, and the test can wear the pearl, so rub lightly. It cannot tell natural from cultured.

Can I test pearls with vinegar?

Don’t. Pearls are calcium carbonate, and GIA warns that all acids damage them — even perfume, hair spray and sweat. Vinegar can only etch a real pearl; it can’t prove anything the drill hole won’t show you safely.

How can you tell if freshwater pearls are real?

The same way: the tooth test, then the drill hole under a loupe. Freshwater pearls are real pearls and, like most pearls sold today, usually cultured. GIA notes they most often come in smaller sizes and near-round or oval shapes, and that China is the leading source.

What are Majorica, shell or “faux” pearls?

Imitations. Majorica pearls are glass beads coated with a “pearl essence” made from guanine extracted from fish scales; shell pearls are shell beads under a thin pearly coating. Under the FTC’s Jewelry Guides, a “faux” or “fashion” pearl must be sold with the word imitation, simulated or artificial, and may not be called real or genuine.

Do knots between the pearls mean they’re real?

No. Knotting protects a strand — if the string breaks you lose one pearl, not all of them, and the pearls don’t rub against each other — but imitation strands can be knotted too. It is a sign of careful stringing, not of real pearls.

Sources and further reading

1. 16 CFR § 23.20 — Misuse of the word “pearl” — Legal Information Institute, Cornell Law School
2. 16 CFR § 23.21 — Misuse of terms such as “cultured pearl,” “real” and “synthetic” — Legal Information Institute, Cornell Law School
3. Pearl: gemstone information — GIA (Gemological Institute of America)
4. What is the difference between natural and cultured pearls? — GIA
5. Majorica Imitation Pearls (Gems & Gemology, Fall 1990) — GIA
6. Shell Pearl as a Pearl Imitation (Gems & Gemology, Summer 2014) — GIA
7. Spiral Nacre in Natural Pearl (Gems & Gemology, Winter 2021) — GIA
8. How does GIA identify whether pearls are natural or cultured? — GIA
9. Pearl Care and Cleaning Guide — GIA
10. What are the main types of cultured pearls? — GIA
11. Pearl Quality Factors — GIA
12. Pearl Buyer’s Guide — GIA
13. Nacre — Wikipedia
14. Pearl — Wikipedia

Links checked November 4, 2026.

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