WHAT GEMMOLOGISTS CHECK

Is that pearl
the real thing?

Grandmother's strand, a market find, a gift.

A strand of cream pearls lying in a loose curve on a pale linen cloth in soft window light, with a small jeweller's loupe beside it — AI-generated image, not a photograph of a real person or place.

Loupe before teeth
Drill holes tell tales
Only a lab says cultured
Simple checks, honest limits

Imitation pearls are glass, plastic or shell beads with a shiny coating. Gemmologists say they are easier to spot than most fake gems, if you know where to look: the surface, the drill holes and the way the colours sit.

Updated 16 October 2026

THE SHORT ANSWER

Real pearls are
never quite perfect.

Imitations are coated beads.
Real pearls are layers of nacre, and it shows.

MAGNIFY

The loupe comes first

Under 10x magnification, imitation pearls show a grainy, glittery, speckled surface. Gemmologist Renée Newman calls magnification the most reliable way to spot them.

Compare the tests

VARIETY

Too perfect is a clue

Real pearls carry small pits and welts, and their overtones vary along a strand. Beads that match exactly in shape, size and colour are a warning sign.

Check a strand

THE LAB

Natural or cultured?

No home test can tell a natural pearl from a cultured one. GIA uses X-radiography to see the pearl's inner structure and settle the question.

See the numbers

A QUICK TEST GUIDE

Which check tells
you what?

Pick a test to see what it can show and how far to trust it. The bar shows how reliable gemmologists consider it for spotting imitations.

Based on GIA and a gemmologist's guide to pearl imitations. For valuable or inherited pieces, ask a qualified gemmologist or a gem laboratory.

Test check

Choose a testWeighing it in your handThe tooth testLooking at the drill holeA 10x loupe on the surfaceA laboratory X-ray

Weighing it in your handA weak hint

A strand that feels unusually light may be plastic. But glass and coated shell beads can feel as heavy as pearls, and some hollow cultured pearls feel light.

The tooth testOften right

Rubbed gently along the edge of a front tooth, real pearls usually feel gritty and imitations smooth. Polished pearls and gritty coatings can fool it.

Looking at the drill holeUseful clue

Cultured pearls usually have sharp, well-defined drill holes. Imitations have a thin coating that may look ragged or form rounded ridges around the hole.

A 10x loupe on the surfaceMost reliable

Imitations look grainy, glittery and speckled at 10x. Real pearls look smoother, with maze-like patterns at about 50x and above.

A laboratory X-rayThe only way

Separating natural from cultured pearls needs a lab. GIA uses X-radiography to see inside the pearl, and it can also separate natural from treated colour.

Sources: Renée Newman, Detecting pearl imitations and treatments (Jewellery Business, 2018); GIA FAQ on pearl identification.

TWO NUMBERS WORTH KNOWING

Soft to the touch,
hard to fake well.

One figure on why pearls need care,
one on how well a fake can hide.

2.5 Mohs

Pearl on the Mohs scale

GIA ranks pearl at 2.5 on the Mohs hardness scale, which means it is very soft and easily scratched or abraded. Store pearls apart from harder jewellery.

HARDNESS · GIA

≈ 9,360

Pearls tested to find one imitation

GIA's Mumbai laboratory tested 18 strands holding about 9,360 pearls. One tiny bead turned out to be an imitation, picked out by its blue reaction under X-ray and an unusually large drill hole.

ONE IN A STRAND · GIA LAB

GIA's lab note (Gems & Gemology, Summer 2025) says common imitations use solid or hollow glass, plastic or shell beads coated with a 'pearl essence' that copies nacre's iridescence.

Several loose pearls of different shapes and soft colours, cream, grey and pale pink, resting in a shallow white porcelain dish — AI-generated image, not a photograph of a real person or place.

FOUR CHECKS TO TRY

A closer look,
no lab needed.

These checks need only good light and a 10x loupe. Use several together: gemmologists warn that no single home test is foolproof.

Look at the surface at 10x
A grainy, glittery, speckled surface points to a coated imitation. Real pearls look smoother at this magnification.
Inspect the drill holes
Look for sharp, clean edges. A ragged coating or rounded ridges around the hole suggest an imitation.
Look for small flaws
Pits, welts and slight differences between pearls are normal for real pearls. Perfect sameness is a warning sign.
Compare the overtones
On good real pearls, soft pink or green overtones vary along the strand. Imitations tend to look the same all the way round.

LOOKING AFTER PEARLS

Last on,
first off.

GIA says pearls can be damaged by many chemicals and all acids, including hair spray, perfume, cosmetics and even perspiration. High heat can burn, discolour, split or crack them.

Never clean pearls in an ultrasonic or steam cleaner. GIA suggests wiping them with a very soft, clean cloth after each wearing, warm soapy water for an occasional thorough clean, and letting a strung necklace dry completely before wearing it.

A hand holding a jeweller's 10x loupe close to a single white pearl on a strand, showing its drill hole — AI-generated image, not a photograph of a real person or place.

Questions

Questions people ask

Does the tooth test really work?

Often, but not always. Real pearls usually feel gritty against the edge of a front tooth and imitations smooth, yet some real pearls are polished smooth and some imitation coatings are made to feel gritty. Magnification is more reliable.

What are imitation pearls made of?

GIA says common imitations use solid or hollow glass, plastic or shell beads coated with a 'pearl essence' substance that copies the iridescence of nacre.

What is the difference between natural and cultured pearls?

Natural pearls form in a mollusc without any human help. Cultured pearls grow after a technician inserts a shell bead and mantle tissue, or tissue alone, into a host mollusc.

Can I tell natural from cultured at home?

No. GIA uses X-radiography, with visual observation and other advanced equipment, to see a pearl's inner structure and decide whether it is natural or cultured.

How should I clean my pearls?

Wipe them with a very soft, clean cloth after wearing. For an occasional thorough clean GIA says warm, soapy water is safe, but never use an ultrasonic or steam cleaner.

Is that pearl
the real thing?