How can I tell if pearls are real?

Rub one lightly against a tooth edge. Real pearls, natural or cultured, feel faintly gritty because of their layered nacre structure, while imitation pearls feel smooth. Distinguishing natural from cultured pearls, however, requires laboratory X-ray testing, since both are genuine nacre and look identical to the eye.

Are pre-1920s pearls always natural?

Not automatically, but they have a much stronger likelihood of being natural, since commercially reliable culturing only became widespread from the 1920s onward. A specific, valuable claim of natural origin should still be confirmed by a gem laboratory rather than assumed from age.

How often should a pearl necklace be restrung?

Roughly every one to two years for a strand worn regularly, since the silk thread it is knotted on stretches and absorbs skin oils over time, increasing the risk of breakage.

Gemstones & cuts

Pearls in vintage jewelry

Natural, cultured or imitation, and why the difference is worth thousands.

Written by our in-house jewelry team · Updated August 1, 2026 · 8 min read

Loose antique cut garnet, emerald, sapphire and diamond stones on a paper parcel — Pearls in vintage jewelry

In short

Before cultured pearls became commercially widespread from the 1920s onward, a fine natural pearl necklace could be worth a fortune, since a natural pearl forms by chance rather than by human intervention and true matched strands were correspondingly rare. That value gap has narrowed the market's attention today mainly to authenticity questions: telling a real pearl from an imitation is a simple test, but distinguishing a natural pearl from a cultured one reliably requires laboratory X-ray imaging, because the difference lies in the pearl's internal structure.

Pearls are one of the few gem materials made entirely by a living creature, and for most of jewelry history that made a naturally formed pearl exceptionally rare and correspondingly expensive, often more valuable than a diamond of similar size. The advent of reliable pearl culturing changed the economics of the gem almost overnight, which is a large part of why so many extraordinary natural pearl pieces from before the 1920s survive today.

For a buyer, the practical questions are simple: is it a real pearl at all, is it natural or cultured, and how do you keep something this soft and organic intact for another century.

Shop the pieces: Pearl, curated and available now.

Natural, cultured or imitation

A natural pearl forms without any human assistance, when an irritant lodges in a wild mollusk and the animal coats it in nacre over years. A cultured pearl forms the same way, by the same nacre-building process, but a bead or tissue is deliberately inserted by a farmer to start it, which produces more consistent, more available pearls than nature does on its own; virtually all pearls sold new today are cultured. An imitation pearl is not a pearl at all, typically a glass or plastic bead coated to look like one.

The gentle tooth test separates real pearls, natural or cultured, from imitations: run a pearl lightly along the edge of a front tooth, and a real pearl feels slightly gritty from its layered nacre structure, while an imitation feels perfectly smooth. This test does not, however, distinguish natural pearls from cultured ones, since both have genuine nacre.

Natural pearl: forms entirely by chance in the wild, no human starting point
Cultured pearl: same growth process, started deliberately with an inserted bead or tissue
Imitation pearl: not a pearl, usually a coated glass or plastic bead
Tooth test: distinguishes real pearls from imitations, not natural from cultured

Why the natural-versus-cultured distinction needs a lab

A cultured pearl typically has a foreign nucleus, often a bead, at its center, surrounded by comparatively thin nacre, while a natural pearl grows nacre in a distinct, layered pattern around a tiny irritant with no manufactured core. That difference is invisible from the outside and only shows up on an X-ray radiograph, which is why gem labs, not jewelers or collectors working by eye, make the natural-versus-cultured determination for any pearl of real value.

For everyday buying purposes, a pearl piece confidently dated to before the 1920s, especially fine matched strands, has a reasonable claim to being natural, but any specific, valuable claim of natural origin should be backed by laboratory testing rather than assumed from age alone.

Caring for pearls

Pearls are soft, organic and porous compared with most gemstones, and they are damaged by the acids in perfume, hairspray and skin oils, so the rule is to put pearls on last, after any beauty products, and take them off first. Wipe them with a barely damp, soft cloth after wearing rather than soaking or ultrasonically cleaning them.

Pearl strands are traditionally knotted between each pearl on silk thread, both to prevent pearls from scattering if the strand breaks and to stop pearls from rubbing directly against each other. That silk stretches and absorbs oils over time, so a strand worn regularly should be restrung roughly every couple of years.

Appraisal document, loupe and precision scale on a jeweler's desk — Gemstones & cuts — from the pieces and workshop notes behind this guide.

Frequently asked questions

How can I tell if pearls are real?: Rub one lightly against a tooth edge. Real pearls, natural or cultured, feel faintly gritty because of their layered nacre structure, while imitation pearls feel smooth. Distinguishing natural from cultured pearls, however, requires laboratory X-ray testing, since both are genuine nacre and look identical to the eye.
Are pre-1920s pearls always natural?: Not automatically, but they have a much stronger likelihood of being natural, since commercially reliable culturing only became widespread from the 1920s onward. A specific, valuable claim of natural origin should still be confirmed by a gem laboratory rather than assumed from age.
How often should a pearl necklace be restrung?: Roughly every one to two years for a strand worn regularly, since the silk thread it is knotted on stretches and absorbs skin oils over time, increasing the risk of breakage.

Written by our estate jewelry team and reviewed by our in-house gemologist. We have been buying and selling European antique jewelry since 1973.

From the reading to the piece