Three bracelets can look identical in the tray, all warm yellow gold, and be worth wildly different amounts: one solid 14K, one gold filled, one plated brass. The stamps sort them out in seconds once you can read them, which is why gold filled vs gold plated is one of the most useful distinctions an everyday jewelry owner can learn.
Solid gold is the same alloy all the way through. Gold filled has a thick layer of real gold mechanically bonded to a base metal core, at least 5 percent of the weight of the metal in the piece under FTC rules. Gold plated carries only a microscopically thin surface layer, usually electroplated, so it wears through quickly and holds essentially no recoverable gold.
Same color, three different objects. Here is how to decode the stamps, what the construction difference means for wear and value, and where the quick tests mislead.
The construction difference, in plain terms
Solid gold jewelry is a gold alloy throughout: usually 10K, 14K, or 18K in the US market, though the FTC guides also allow lower karats such as 9K to be sold as gold when the fineness is disclosed, with the karat number describing what fraction of the alloy is pure gold (24ths, so 14K is 14/24 gold). Scratch it anywhere, at any depth, and you find the same metal. The alloy recipe, not just the karat, also decides color; if a piece looks pink or reddish rather than plain yellow, rose gold vs yellow gold explains what that copper-rich mix means for the metal underneath.
Gold filled is a sandwich. A sheet of karat gold is mechanically bonded, with heat and pressure, onto a base metal core (usually brass), and the bonded stock is then formed into jewelry. The gold is a genuinely thick layer, which is why gold-filled pieces from the mid-1900s often still look gold today. Under the FTC Jewelry Guides, an item marked “gold filled” must carry a karat gold layer of at least 10 karat fineness that makes up at least 1/20, that is 5 percent, of the weight of the metal in the article. Note the denominator: it is the metal, not the finished piece, so set stones do not count toward it. The marking must also state the karat of that layer, which is why the classic stamp reads “1/20 12K GF.”
Gold plated jewelry starts as a finished base-metal piece that is then electroplated with gold. The electric current deposits a film measured in fractions of a micron to a few microns. The FTC floor for calling something gold electroplate is 0.175 microns, and 2.5 microns for heavy gold electroplate, against a bonded gold-filled layer that is thicker by a wide margin. It looks perfect on day one; the difference is what happens by year one.
Decoding the stamps
Most gold-look jewelry tells you exactly what it is, in abbreviations:
- 1/20 12K GF (or 1/10 10K GF, 1/20 14K GF): gold filled. The fraction is the gold layer’s share of the weight of the metal in the piece, the karat is the layer’s fineness.
- RGP (rolled gold plate): same bonded-sheet construction as gold filled but with a thinner gold layer, below the 1/20 threshold. The FTC requires the actual fraction to be disclosed, so you see stamps like “1/40 10K RGP.” Common on vintage watch cases.
- GEP or “gold electroplate”: electroplated gold. The FTC Jewelry Guides set a minimum plating thickness of 0.175 microns for the unqualified term, and the gold used must be at least 10 karat fineness.
- HGE (heavy gold electroplate): still electroplate, just thicker; the FTC threshold for “heavy” is 2.5 microns, again at 10 karat fineness or better. Despite the confident-sounding name, HGE is plated costume jewelry.
- Vermeil: gold coated or plated over sterling silver rather than brass. Under the FTC guides, vermeil must be sterling silver coated with gold of at least 10 karat fineness and at least 2.5 microns thick. The silver base gives it real, if modest, metal value; a 925 stamp on a gold-colored piece is the giveaway, which we cover in what 925 means on jewelry.
- 10K / 14K / 18K / 585 / 750 alone, with no GF, RGP, or plating qualifier: the piece is claiming to be solid gold. The three-digit versions are parts-per-thousand fineness (585 is 14K, 750 is 18K).
One caution that applies to every stamp: a mark is a regulated claim, not a guarantee. Fake karat stamps exist on plated pieces, so pair the stamp with the wear and weight checks below.
Gold filled vs gold plated: how they wear over time
Time is the most honest test, and on secondhand jewelry the wear has already happened for you. Look at the friction points: clasp edges, the underside of a bracelet, ring shanks, chain links that rub.
- Solid gold wears slowly and stays gold-colored everywhere, because there is nothing underneath to expose. Scratches just reveal more gold.
- Gold filled holds its color for years and often decades of normal wear. When it finally does wear through, it shows dull gray or brassy base metal at high-contact spots, typically as a gradual dulling rather than flaking.
- Gold plated can wear through at contact points within months of regular wear. Look for brassy or coppery patches, a greenish tinge on the metal or reported skin discoloration, and in cheap pieces actual flaking or bubbling of the coating.
A bracelet is ideal for this inspection because it lives in constant contact with desks and tables; our bracelet identification guide shows exactly where the wear shows first and what else clasps and links reveal.
What each is worth, stated plainly
Label the numbers correctly, because “worth” means different things here.
- Solid gold has melt value: the piece’s weight times its gold fraction times the gold price. Resale as finished jewelry can sit above melt for signed, antique, or desirable pieces, but melt is the floor. This is why solid gold is the only category buyers weigh on a scale first.
- Gold filled has modest but real recoverable gold, on the order of a few percent of the piece’s weight. Specialist refiners buy gold-filled scrap in bulk, though the per-piece melt value is small. Resale value usually comes from the piece itself: vintage gold-filled watch cases, signed costume pieces, and Victorian gold-filled lockets sell as objects, not as metal.
- Gold plated has effectively zero melt value; the gold film is too thin to recover economically. Any resale value is purely as fashion or as a collectible brand name.
- Vermeil carries silver melt value from its sterling base plus whatever the design brings, but not gold value.
The pattern generalizes: below solid gold, value comes from what the piece is, not what it is made of. Maker, era, design, and condition, the levers explained in what makes jewelry worth more, decide whether a gold-filled or plated piece is a throwaway or a genuinely collectible object. And before you anchor on any figure, be clear which number you need: melt, realistic resale, or insurance replacement, which our guide to what your jewelry is worth breaks down.
Quick checks, and the magnet myth
A practical order of operations for an unmarked or suspicious piece:
- Hunt for stamps on clasps, tags, ring shanks, and edges, and read them against the decoder above.
- Inspect wear points for base metal showing through.
- Feel the weight. Solid gold is dense; a large piece that feels oddly light is usually hollow or base metal. This is a rough signal, not a measurement.
- Use a magnet correctly. Gold is not magnetic, but neither are brass and copper, the usual cores of filled and plated jewelry. A strong pull on the body of the piece means a ferromagnetic core, iron, nickel, or steel, so not solid gold; no pull proves nothing. The magnet can only rule out, never confirm.
If you want a fast first read, scan the piece with GemPeek: it identifies the likely type, reads visible stamps and wear, and estimates a value range, which you should treat as a starting point and confirm with an appraiser or a metal test before selling anything potentially solid gold. For definitive metal content, jewelers and refiners use acid tests, electronic testers, or X-ray fluorescence, and that confirmation is cheap insurance on any piece the checks above cannot settle.
The bottom line
Read the stamp first: GF and RGP mean a bonded layer of real gold with a little recoverable value, GEP and HGE mean thin electroplate with none, vermeil means gold over sterling, and an unqualified karat mark claims solid gold. Then make the piece prove it with wear inspection and weight. Ten minutes with a loupe sorts almost any gold-colored tray into metal value, object value, and costume, and that sorting is exactly what stops people from scrapping a good piece or overpaying for a plated one.