You find a pearl necklace in your grandmother's jewelry box. It looks beautiful, but you have no idea if it's worth $500 or $5. That's not an unusual situation. A generation or two ago, most women owned pearl jewelry, and a surprising share of it was imitation. Knowing which you're dealing with changes everything about what you do next.
The good news is that you can run several reliable tests at home, with no equipment and no expertise. You don't need to hand over a potential treasure to a stranger before you know what you actually have.
Run the tooth test first
Take one pearl and lightly drag it across the biting edge of your upper front teeth. A real pearl feels gritty, like fine sandpaper. A fake pearl feels smooth and glassy, almost frictionless. The difference is usually immediate and obvious.
The grittiness comes from the nacre, the material a mollusk builds up in microscopic layers around an irritant over months or years. Those crystalline layers create a slightly rough surface that no synthetic coating can fully replicate. Glass and plastic beads, which make up most imitation pearls, feel completely smooth.
One caveat: some high-end fakes, particularly shell pearls, are made from ground mollusk shell and can pass this test. If you get a gritty result, it's a strong positive sign, but keep going through the other tests before drawing conclusions.
Look at the luster closely
Set the pearls on a white piece of paper in natural light and look at how they reflect. Real pearls have depth. The glow seems to come from inside the pearl rather than sitting on the surface. You can often see your own reflection in a well-made cultured pearl, and there's a softness to the light even in the brightest spots.
Fake pearls have a shiny surface, but it sits on top. The reflection looks flat and uniform, almost plasticky. Some descriptions call it a “ball-bearing shine.” Real pearls show what experts call orient, a subtle shifting iridescence, like a thin film of oil on water, that moves slightly as you tilt the piece.
Color variation across a strand is also telling. In a genuine necklace, each pearl reflects light slightly differently because every pearl has minor surface differences. If every single bead looks identical, and the shine is uniform from end to end, that's a factory product.
Check the surface and shape
Real pearls are almost never perfectly round. Even in expensive strands of Japanese Akoya pearls, known for their near-perfect matching, you can still find slight variations in shape from bead to bead. Freshwater cultured pearls are often noticeably irregular, oval, or baroque. A strand of absolutely identical, flawless spheres is a red flag.
Look at the surface closely, under a magnifying glass if you have one. Genuine pearls will have minor natural imperfections: small ridges, tiny dips, faint blemishes. These aren't flaws so much as evidence that something living made this. Imitation pearls tend to look too smooth and too perfect. If you do see blemishes on a suspected fake, look for a different kind: chipping or peeling at the surface, which indicates a coating over a plastic or glass core.
Under 10x magnification, real nacre has a characteristic appearance that gemologists describe as smooth and slightly scaly, like fish scales. Imitation coatings look coarser and more irregular at that level of magnification, even if they look better to the naked eye.
Examine the drill holes
Flip the strand over and look carefully at the holes where the string passes through each pearl. On a real pearl, the drill hole tends to be small and clean, with sharp, well-defined edges. Pearls are sold by weight, so sellers have an incentive to drill as small a hole as possible to preserve that weight.
On imitation pearls, the holes are often larger because the base bead is cheaper and the stringing material can be thicker. Around the hole you may see signs of peeling or chipping where the coating has separated from the bead underneath. You might also see a buildup of the pearlescent coating material, a slight ridge or discoloration at the edge of the hole where the liquid coating pooled during manufacturing.
If the coating has chipped away anywhere on the strand, look at what's underneath. A glass bead or a white plastic sphere is your answer right there.
Pick them up and feel the weight
Real pearls have noticeable heft for their size. Nacre is dense, and even a modest strand of cultured pearls has real substance when you hold it. Plastic imitations feel light, sometimes almost hollow.
This test has limits. Some imitation pearls use glass cores, which are heavy enough to feel convincing. But if a pearl necklace feels almost weightless in your hand, it's very likely fake. Genuine cultured pearls should feel cool at first touch before warming quickly to your skin temperature. Plastic pearls stay at room temperature.
Check what they're strung on
A genuine pearl necklace in good condition will almost always be strung on silk thread with a small knot tied between each individual pearl. The knots serve two purposes: they prevent the pearls from rubbing together and wearing down the nacre, and they stop all the pearls from scattering if the string breaks. The knots are usually the same color as the thread, which is typically white or cream.
Imitation pearl strands are often strung without knots, or on nylon or cotton thread. A cheap plastic clasp is also a strong indicator. Genuine pearls are worth protecting with quality stringing and hardware. If the clasp is marked 14K, 18K, or 925 (sterling silver), that's a positive sign. A clasp made from pot metal or plated base metal suggests the whole piece was made to a budget that didn't include real pearls.
What real pearls are actually worth
Even if your tests confirm the pearls are genuine, managing expectations matters. Most cultured pearl necklaces from a generation or two ago are worth less on the resale market than people expect. A standard strand of freshwater cultured pearls might bring $50 to $200 on resale, even if the original retail price was much higher. Quality Japanese Akoya pearl strands in good condition can sell for $300 to $2,000 depending on size and luster. South Sea or Tahitian pearls are the high end, with retail prices from several thousand dollars up to six figures for exceptional strands.
Natural pearls, formed without human intervention, are almost nonexistent in today's retail market and are primarily found in antique jewelry or sold at auction. If you suspect you have a natural pearl rather than a cultured one, that requires X-ray testing by a certified gemologist. The presence of a bead nucleus inside a cultured pearl shows up on X-ray; a natural pearl has a different internal structure entirely.
Branded jewelry adds a different layer of value. A Mikimoto clasp can turn a strand worth a few hundred dollars into one worth several thousand. Look for a stamped “M” in an oyster shell outline on the clasp, and any paperwork or original box you can find.
When the tests aren't enough
Home tests can eliminate most fakes and confirm most genuine pearls, but they can't tell you whether cultured pearls are natural, identify the specific type of pearl, or give you a reliable dollar figure for insurance or sale. For any of those purposes, take the piece to a certified gemologist, ideally one with specific experience in pearls. A written appraisal typically costs $50 to $150 and is worth it if the pearls look like they might be something significant.
If the tests come back negative and what you have is imitation, that's not necessarily the end of the story. Some vintage costume pearl jewelry has collector value on its own terms, and a pretty strand of faux pearls from the 1950s can be sold on eBay or at an estate sale without pretending it's anything it's not.
