Real or Costume Jewelry? How to Tell in Ten Minutes

Every inherited jewelry box holds three kinds of thing tangled together: fine jewelry in gold, silver or platinum with real stones; costume jewelry made to look like it; and a third pile people forget exists — costume pieces that are worth real money because of who made them. Sorting the box takes about ten minutes, a loupe and good light, and the clues are the same for rings, earrings, brooches and necklaces. You are looking at four things: what’s stamped, how the stones are held, how the parts are made, and how the piece has worn.

1. Read the marks

Fine jewelry usually tells you what it is. Look on the inside of ring bands, on clasps and the tongues of box clasps, on earring posts and on the backs of pendants and brooches. A fineness number — 375, 585 or 750 for gold, 925 for sterling silver, 950 for platinum — or a karat mark like 14K is a claim of solid precious metal.

Costume jewelry is marked too, just differently. GP, GEP, HGE, RGP, GF and fractions like 1/20 12K mean a layer of gold over base metal. A name on its own, without a fineness mark — Trifari, Monet, Napier, Coro, Sarah Coventry, Weiss — is a costume maker’s signature, and is the first clue to the collectible pile. Our stamp decoder reads the metal marks if you’re unsure.

2. Turn it over: how the stones are held

This is where costume jewelry gives itself away most often. In fine jewelry a stone is set: held by metal prongs, a bezel rim or a channel, with the back usually open so light can enter the stone. In mass costume jewelry, stones are frequently glued into cups — look for a shiny film or yellowed adhesive around the edge — and many rhinestones have a mirror-like foil on the back to make cheap glass sparkle. A stone that has fallen out and left a clean, glue-smeared hole is a costume piece.

One honest exception: genuinely old fine jewelry, from before about 1850, was often made with closed, foiled backs too, because the cuts of the day needed help to shine. A closed back on a hand-made gold ring with rose-cut diamonds is a reason to look harder, not to dismiss it — see how to date a vintage ring.

3. Look at the stones themselves

• Facet edges. Under a loupe, the edges where facets meet are crisp on diamond, sapphire and ruby. Glass and soft stones show rounded, chipped or scuffed edges after a few years of wear.
• Bubbles and swirls. Round gas bubbles and flowing swirl lines are the signature of glass. Natural stones have crystals, feathers and needle-like inclusions instead.
• Mould marks. Moulded glass stones can show a seam or a slightly dished, rounded table rather than flat, polished facets.
• Too big, too perfect. A flawless, richly coloured “emerald” the size of a thumbnail on a light, thin band is almost certainly glass or a lab-made stone. Real gems at that size are rare and set accordingly.

For diamonds specifically — and the lookalikes that fool home tests — see how to tell if a diamond is real, and for coloured stones, how to identify the gemstone in a ring.

4. Check the hardware

The small parts are where manufacturers save money, so they’re revealing.

• Jump rings and links. On fine chains and bracelets the little connecting rings are usually soldered closed. On costume pieces they’re often just bent shut, with a visible gap.
• Clasps. A box clasp with a safety catch, or a stamped lobster clasp, suggests fine work. A thin, unmarked spring ring is common on both — read the mark on it if there is one.
• Earring posts and pin stems. Fine earrings have posts in the same metal as the earring and are usually marked. A steel post on a “gold” earring is a costume tell.
• Construction. Fine pieces are cast or hand-built from solid metal; much costume jewelry is stamped from thin sheet, hollow behind, with seams you can see.

5. Weight, wear and tarnish

Precious metals are dense. A gold ring feels heavier than a plated brass ring of the same size, and platinum feels heavier still. Wear tells you the rest: plating rubs through on high points and edges to show a brassy, coppery or grey base, and base metals turn green or flake. Silver goes the other way — sterling darkens to a grey-black tarnish that polishes off, which plated base metal rarely does. For rings, our guide to testing gold at home covers the magnet, the ceramic tile and the density test in detail.

Pearls: the tooth test, done politely

Rub a pearl gently along the edge of your front teeth. Natural and cultured pearls feel slightly gritty, because their surface is made of tiny overlapping platelets of nacre; glass and plastic imitations feel glassy smooth. Two more clues: real pearls on a strand are usually knotted between each pearl, and they’re rarely perfectly identical in shape and colour.

The third pile: costume jewelry that’s worth money

“Costume” describes the materials, not the value. Signed pieces from the great twentieth-century makers — Miriam Haskell, Trifari, Eisenberg, Schiaparelli, Hattie Carnegie, and Chanel’s costume line — have collectors of their own, and well-preserved examples sell for far more than their metal. A few things to know before anything goes in the donation bag:

• Look for a signature on the back, the clasp or a small oval plaque. Many good pieces are signed; some early ones aren’t.
• Condition is everything. Missing stones, worn plating and darkened foil cut collectible value sharply. Don’t re-glue or re-plate anything before an expert has seen it.
• Bakelite — the heavy, warm-coloured early plastic of 1930s bangles and brooches — is collectible in its own right. Rubbing it with a metal polish such as Simichrome leaves a yellow residue on genuine Bakelite, and hot water releases a faint chemical smell; later plastics don’t do either.

Fine metal marks

375, 585, 750, 925, 950, 10K–18K, PT

Costume metal marks

GP, GEP, HGE, RGP, GF, 1/20 12K

Stones

Set and open-backed vs glued and foil-backed

Glass tells

Round bubbles, swirls, rounded facet edges

Hardware

Soldered links and marked clasps vs open jump rings

Don’t discard

Signed vintage costume and Bakelite

The takeaway

Most of the sorting happens before you touch a test kit: read the marks, turn the piece over, look at the stones and the hardware under a loupe, and feel the weight. What’s left — unmarked metal, a stone you can’t place, a signed costume piece in good condition — is what deserves a jeweler’s or a specialist dealer’s eye. If you’re thinking of selling what you’ve found, how to sell a ring explains who pays what, and why.

At a glance

Fine vs costume jewelry at a glance

Clue	Fine jewelry	Costume jewelry
Marks	375, 585, 750, 925, 950, 10K–18K, PT	GP, GEP, HGE, RGP, GF, or a maker’s name alone
Stones	Set in prongs, bezels or channels; usually open backs	Often glued; foil-backed rhinestones
Stone surface	Crisp facet edges, natural inclusions	Rounded edges, bubbles, swirls
Links and clasps	Soldered links, marked clasps	Open jump rings, unmarked hardware
Wear	Same colour underneath	Plating rubs through; green or flaking

Frequently asked questions

How can I tell if my jewelry is real gold?

Look for a fineness or karat stamp without GP, HGE, RGP or GF beside it, check that a magnet doesn’t pull, and look for base metal showing where it wears. A jeweler’s acid or XRF test confirms.

Is costume jewelry worth anything?

Most is worth little, but signed vintage pieces from makers such as Miriam Haskell, Trifari, Eisenberg and Schiaparelli, and genuine Bakelite, have collectors and can sell for real money in good condition.

How do I tell a real pearl from a fake?

Rub it gently along your front teeth: real pearls feel slightly gritty, imitations glassy smooth. Real strands are usually knotted between pearls.

Does a closed back always mean costume jewelry?

No. Fine jewelry made before about 1850 often has closed, foiled backs. On a hand-made gold piece with old-cut stones, a closed back is a reason to look harder.

Sources and further reading

1. 16 CFR Part 23 — Guides for the Jewelry, Precious Metals, and Pewter Industries — U.S. Electronic Code of Federal Regulations
2. Costume jewelry — Wikipedia
3. Rhinestone — Wikipedia
4. Gold-filled jewelry — Wikipedia
5. Bakelite — Wikipedia

Links checked October 4, 2026.