October 06, 2026

How to Tell If Pearls Are Real: The Tooth Test and Better Ones

By Sasha Tarasova

Filed under Gemstone GuidesBuying GuidesCare, Sizing & Insurance

Short answer: to tell if pearls are real, rub one gently along the edge of your front teeth: real pearls, natural or cultured, feel slightly gritty, while glass and plastic imitations feel smooth. Then inspect the drill holes with a loupe for flaking coating, and look for small variations between pearls. Only a gem laboratory can tell a natural pearl from a cultured one.

"Real" means something specific here. A real pearl, in this guide, is one grown by a mollusc, whether it formed by chance (a natural pearl) or around a nucleus inserted by a pearl farmer (a cultured pearl). An imitation is a manufactured bead, usually glass, plastic or shell, coated to look like one. Telling natural from cultured is a separate problem, covered in our guide to natural and cultured pearls in antique jewelry. This guide is about the first and more common question: is it a pearl at all?

What makes a real pearl different from a fake?

A real pearl is built from nacre, layer upon layer of microscopic aragonite platelets (a crystal form of calcium carbonate) held together by an organic protein called conchiolin. Those overlapping platelets give real pearls their depth of lustre and their faintly rough surface texture. Imitations copy the look with a coating on a bead; the texture and structure underneath are different, and that is what every useful test exploits.

The imitations you are likely to meet:

• Glass pearls. A glass bead coated with a lustrous lacquer, historically including "essence d'orient", a preparation made from fish scales. Heavy, cool to the touch and often very convincing at a distance. Much vintage costume jewelry uses them.
• Plastic pearls. Light, warm to the touch, often perfectly uniform, and usually the easiest to spot.
• Coated shell pearls. A bead ground or cut from shell, coated with a pearly finish. Heavier and more convincing than plastic.
• Majorica-type pearls. Man-made pearls of the kind made on Mallorca, with a glass core and multiple layers of lustrous coating. They are sold openly as man-made, and good ones are handsome, but they are not pearls grown by a mollusc. Majorica is a brand name; we use it descriptively and are not affiliated with the company.

None of these is dishonest in itself. A strand of good glass pearls sold as glass pearls is a fair object. The problem is only when one is sold, or inherited, as the real thing.

The tests compared

Here is what each test can tell you, how much to trust it, and what it risks doing to the pearls.

How do you do the pearl tooth test?

The tooth test is the best single home test for real versus imitation pearls. Your tooth enamel is sensitive enough to feel the edges of the nacre platelets, which a coating cannot fake convincingly.

1. Clean your teeth first and remove lipstick. Food, toothpaste residue and cosmetics are harmful to pearls.
2. Hold the pearl lightly and rub it gently, side to side, along the biting edge of your front teeth. Do not bite.
3. Feel for texture. A real pearl feels faintly gritty or sandy, like very fine sandpaper. An imitation feels smooth and glassy, and sometimes slippery.
4. Test several pearls on a strand, not just one. Repairs and replacements happen.
5. Wipe the pearls afterwards with a soft, slightly damp cloth, then let them dry flat.

Its limits are real. Natural and cultured pearls both feel gritty, so the test tells you nothing about which you have. A small number of imitations have textured coatings. Avoid it with veneers, crowns or sensitive teeth, and skip it on fragile or badly worn antique pearls whose surface is already thin.

What do the drill holes tell you?

The drill holes are where imitations give themselves away, because the coating is thinnest and most exposed there. Look with a 10x loupe and good light.

• Imitation pearls often show the coating chipped, flaked or peeling around the hole, with glass, plastic or shell visible underneath. Sometimes the coating forms a small ridge or lip where it pooled during manufacture.
• Real pearls show a clean, crisp hole edge. You may see the nacre as a distinct layer, and on bead-nucleated cultured pearls a visible boundary between the nacre and the shell bead inside.
• Wear on a real pearl shows as a dulled, slightly worn surface near the hole; on an imitation it shows as the coating wearing through to a different material.

Old strands can hide their holes behind knots. Turn each pearl gently on the silk rather than forcing anything.

Are perfectly matched pearls a sign of fakes?

Not on their own, but perfection is suspicious. Real pearls vary. Look along a strand in daylight and real pearls usually show slight differences in shape, size, surface marks, overtone (the secondary colour that floats over the body colour, such as rose or green) and lustre. Imitations made in a factory tend to be identical: the same size, the same even colour, no blemishes at all.

The complication is that fine cultured strands are matched with great care, and expensive ones can look very uniform. So use uniformity as a prompt to look harder, not as a verdict. What imitations rarely manage is the depth of lustre: a real pearl with good nacre gives sharp reflections that seem to sit below the surface, while a coating tends to look glossy on top and flat underneath.

What does a real pearl surface look like under magnification?

Under a loupe or low-power microscope, nacre shows fine, irregular contour lines, a little like a topographic map, where the edges of the platelets meet the surface. Imitations look either perfectly smooth or evenly granular, like fine paint. Small natural blemishes, pits and bumps are normal on real pearls.

This takes practice. It is most useful as a second test alongside the tooth test and the drill holes, not as your only one.

Do weight and temperature tell you anything?

A little. Real pearls feel cool at first and warm up slowly against the skin, while plastic imitations feel warm and light from the start. Glass imitations, however, are also cool and often heavier than real pearls, so a cool, heavy strand can still be glass. These are clues for ruling out cheap plastic, not tests.

Which pearl tests are myths or dangerous?

Never test pearls with a flame, a blade, a pin or an acid, however the video on your phone presents it. Pearls are among the softest materials in jewelry, around 2.5 to 4.5 on the Mohs scale, and they are damaged by heat and by acids. Our Mohs hardness guide explains what that means for everyday wear.

• The flame test. The claim is that real pearls do not burn. Heat can crack, discolour or dull nacre and will damage the silk thread. It proves nothing you cannot learn safely.
• The scratch test. Scraping with a knife or needle to see what is underneath removes nacre or coating permanently.
• The vinegar test. Real pearls react with acid because nacre is calcium carbonate. That is exactly why the test is a bad idea: it dissolves the surface of the pearl you are trying to identify.
• The hard rub. Rubbing two pearls together firmly can leave a fine powder on real pearls, but it also scuffs them. If you try it, do it lightly and briefly, and prefer the tooth test.

What does the clasp and stringing tell you?

The fittings are circumstantial evidence. A fine strand of real pearls is usually knotted between each pearl on silk, so that a break loses only one pearl, and fastened with a gold, platinum or silver clasp, often stamped. Cheap imitations are more often strung without knots on nylon, with a base-metal clasp. Our guides to gold stamps and to testing whether gold is real will help you read the clasp.

But clasps are swapped, imitations are sometimes knotted on silk, and real pearls are often restrung on whatever was to hand. A fine clasp on a strand of glass pearls, or the reverse, is common. If there are diamonds in the clasp, our guide on how to tell if a diamond is real covers those.

A home checklist for pearls

1. Look along the strand in daylight for small natural variations and for depth of lustre.
2. Do the tooth test gently on several pearls.
3. Inspect the drill holes with a loupe for flaking coating or a visible glass or plastic core.
4. Check the surface under magnification for fine contour lines.
5. Read the clasp and stringing as supporting evidence only.
6. Never use flame, blades, pins or acids.
7. For value, insurance or sale, send it to a laboratory.

When should you see a professional?

See a qualified gemologist whenever the pearls might be natural, whenever you are buying or selling a strand of significant value, and whenever you need documentation. Home tests can tell real from imitation with reasonable confidence; they cannot tell natural from cultured, and that distinction can be the difference between a modest valuation and a very large one.

The definitive method is X-radiography, which shows a pearl's internal structure. A cultured pearl usually reveals the bead nucleus inside; a natural pearl shows concentric growth layers without one; an imitation shows a solid glass or plastic core. Major gem laboratories, including the GIA and specialist European labs, issue pearl reports on this basis. It is non-destructive.

If the strand is old, have a jeweler check the silk at the same time. Silk stretches and weakens with wear, and a strand that breaks scatters pearls that are hard to replace. Documentation from a laboratory is also what an insurer will want; our guide to insuring antique jewelry covers appraisals and riders.

If you are buying rather than checking, the burden belongs with the seller. A straight dealer will say whether pearls are natural, cultured or imitation, and whether a laboratory has confirmed it; our note on what a dealer should disclose sets out what to expect, and our guide to buying antique jewelry online covers the questions to ask before you pay.

Questions people actually ask

Does the tooth test really work on pearls?

Yes, for telling real pearls from imitations. Real pearls, natural or cultured, feel slightly gritty when rubbed gently along the edge of your front teeth, because of the overlapping nacre platelets. Glass and plastic imitations usually feel smooth. The test cannot tell natural pearls from cultured ones, and a few imitations have textured coatings, so combine it with a drill hole inspection.

Are cultured pearls real pearls?

Yes. Cultured pearls are grown by a living mollusc, like natural pearls; the difference is that a farmer starts the process by inserting a nucleus or piece of tissue. They are made of real nacre and pass the tooth test. Natural pearls, which formed without human help, are much rarer and are identified by a laboratory using X-radiography.

Are Majorica pearls real?

Majorica-type pearls are man-made, not grown by a mollusc. They have a glass core coated with multiple layers of lustrous finish, and they are sold openly as man-made pearls. Good examples are attractive and durable, but they are imitations in the gemological sense and are valued accordingly, not as natural or cultured pearls.

How can you tell if vintage pearls are real?

Use the same tests: the tooth test, the drill holes and the look of the strand. Vintage costume jewelry often used glass pearls, whose coating tends to wear through at the drill holes with age, which makes them easier to spot. Real vintage strands may be natural or cultured, and only a laboratory can tell which.

Do real pearls feel cold?

Real pearls usually feel cool at first and warm slowly against the skin. Plastic imitations feel warm and light from the start. Glass imitations, however, also feel cool and can be heavier than real pearls, so temperature alone cannot confirm anything. Treat it as a way to rule out cheap plastic, not as a test.

Can you test pearls with a lighter?

No. Heat can crack, discolour and dull real nacre, and it will damage the silk they are strung on. The claim that real pearls survive a flame unharmed is unreliable, and the test risks ruining the strand you are trying to identify. Use the tooth test and a loupe instead, and a laboratory for certainty.

What is the most reliable way to test pearls?

X-radiography at a gem laboratory. It shows the internal structure of each pearl, revealing a bead nucleus in most cultured pearls, concentric growth layers in natural pearls and a solid core in imitations. It is non-destructive and is the basis of laboratory pearl reports. At home, the tooth test plus a drill hole inspection is the best combination.

Every pearl we list is described as natural, cultured or imitation, and you can browse our antique and vintage jewelry with that in mind. If you want a particular strand or pair of pearl earrings found and properly documented, our sourcing service runs the search. More on stones and organic gems sits in our gemstones archive.