Jewelry Stamps & Hallmarks Guide: What Every Mark Means

Most jewelry buyers never decode the tiny stamps on their pieces — but those marks are the most honest thing a jeweler puts on their work. A ring stamped "18K 925 GP" tells you the gold karat, the base metal, and the plating method in four characters. A piece with no stamp tells you the seller doesn't want you to know what you're buying.

This guide decodes every jewelry stamp you're likely to encounter — gold purity numbers, plating abbreviations, silver marks, and the combinations that appear on real pieces. Use the section links to jump to specific stamps.

What's in this guide

• Gold purity numbers: 375, 417, 585, 750, 999
• Gold plating stamps: GP, GF, GE, HGE, RGP
• 18KGP — what it means specifically
• HGE — Heavy Gold Electroplate
• Silver stamps: 925, 800, 999, Sterling
• Vermeil — the premium gold-over-silver standard
• How to read stamp combinations
• What no stamp means
• FAQ

Gold Purity Numbers

Gold purity stamps are three-digit numbers representing the parts of gold per thousand. They're the international standard — used in Europe, Asia, and the Middle East — and correspond directly to the karat system used in the US.

For a full breakdown of each purity level, see: gold purity numbers and hallmarks guide.

Gold Plating Stamps

Plating stamps tell you how the gold was applied. They're often combined with a karat number and/or a base metal purity number:

For the full comparison: complete guide to gold plating stamps (GP, GF, HGE, GE).

18KGP — What It Means

18KGP (also written 18K GP or 18KGP) means the piece is plated with 18-karat gold — 75% pure gold applied through electroplating. The "18K" tells you the gold purity; "GP" tells you it's plated, not solid. When you also see "925" on the same piece, the base metal is sterling silver — the best possible base for gold plating.

18KGP is the most common stamp on quality gold-toned fashion jewelry because 18K gold produces the rich yellow color most buyers associate with "real gold," while plating keeps the price accessible. A well-made 18KGP piece on a 925 sterling silver base is hypoallergenic, tarnish-resistant with proper care, and visually identical to solid 18K gold.

→ Full breakdown: what does 18KGP mean — value, durability, and what to look for

HGE — Heavy Gold Electroplate

HGE stands for Heavy Gold Electroplate. It's an older plating designation that was popular on US and European jewelry from the 1950s through the 1980s. "Heavy" signals a thicker-than-standard electroplated gold layer — typically 2.5 microns or more, compared to the 0.5–0.175 micron minimum for standard gold electroplate.

HGE is most often found on vintage pieces: estate jewelry, old Monet pieces, Napier, and similar brands. The stamp tells you the piece was made to a higher durability standard than flash-plated fashion jewelry. When you see "18K HGE" or "14K HGE," the karat number tells you the gold purity of that thicker layer.

→ Full breakdown: what does HGE mean on jewelry — 18K HGE, 14K HGE explained

Silver Stamps

Silver purity stamps follow the same parts-per-thousand system as gold:

The 925 stamp is the one you'll encounter most often. Importantly: if you find a 925 stamp on a gold-colored piece, it's not a mistake — 925 describes the sterling silver base metal, while the gold layer is described separately. See: what does 925 mean on jewelry.

Vermeil — The Premium Standard

Vermeil (pronounced "ver-MAY") is a legally defined jewelry category in the US: gold plating of at least 10K (typically 18K) applied to a 925 sterling silver base at a minimum thickness of 2.5 microns. Those three requirements — gold quality, base metal, and thickness — make vermeil the most reliable electroplated finish you can buy.

Unlike plain "GP" stamps where the base metal and layer thickness are unknown, vermeil tells you exactly what you're getting. A piece labeled "vermeil" must meet the FTC standard or the seller is misrepresenting the product. See: what is gold vermeil.

How to Read Stamp Combinations

Most pieces carry more than one stamp. Here's how to read the common combinations:

• "18K 925" or "925 18K" — 18K gold plated over 925 sterling silver. Best gold-plated combination — gold quality AND base metal both confirmed. Both hypoallergenic.
• "18KGP" — 18K gold plated. Gold purity confirmed; base metal not specified. Ask the brand what the base is.
• "14K GF" — 14K gold filled. The standard US gold-filled specification: mechanically bonded gold layer comprising at least 1/20 of total weight in 14K gold.
• "18K HGE" — 18K heavy gold electroplate. Thicker than standard plating; common in vintage pieces.
• "585" alone — solid 14K gold. No plating.
• "750" alone — solid 18K gold. No plating. Fine jewelry.
• "925" alone on a silver piece — sterling silver. No gold involved.
• No stamp — unknown. See below.

What No Stamp Means

A piece with no stamp at all is telling you something: the seller doesn't want you to know the material. In many countries, precious metal jewelry is legally required to carry a purity mark. No stamp in that context means either the piece isn't precious metal — or the seller is avoiding accountability.

Fashion alloy jewelry (zinc, brass, nickel-plated base metals) often carries no stamp. This isn't illegal in the US for fashion jewelry, but it means you should assume the worst: nickel-containing base metals, flash-thin gold coating, and potential for skin reactions. If you have sensitive skin, the absence of a 925 or similar stamp is a clear signal to look elsewhere.

Frequently Asked Questions

What does 18K stamp mean on jewelry?

18K on solid gold jewelry means the piece is 18-karat gold — 75% pure gold, with 25% alloy metals added for strength. 18K is the most common fine jewelry standard worldwide. If "18K" appears alongside "GP," "GF," or "HGE," it describes the purity of the gold layer on a plated piece, not solid gold.

What jewelry stamps mean real gold?

Stamps indicating solid gold: 375 (9K), 417 (10K), 585 (14K), 750 (18K), 916 (22K), 999 (24K), or the corresponding karat marks (10K, 14K, 18K, etc.) alone. If you see GP, GF, HGE, or GE alongside the karat number, the piece is plated — not solid gold. Both are legitimate; they're just different products.

What does 925 mean on a gold ring?

925 on a gold-colored ring means the base metal is 925 sterling silver (92.5% silver). The gold color comes from a plating layer. This is actually a positive sign — sterling silver is the best possible base for gold plating, being hypoallergenic and non-tarnishing even when the plating eventually wears. Look for a karat number (like "18K") alongside the 925 to confirm the gold quality.

What is the difference between GP and GF jewelry?

GP (Gold Plated) is a thin gold layer deposited by electroplating — typically 0.5–2.5 microns. GF (Gold Filled) is a much thicker gold layer mechanically bonded to the base under heat and pressure. US regulations require gold-filled pieces to be at least 1/20 gold by weight. GF lasts 10–30 years; GP lasts 2–5 with good care on a quality base. GF costs more because it contains significantly more gold.

What does HGE mean on old jewelry?

HGE means Heavy Gold Electroplate — a thicker-than-standard electroplated gold layer, typically 2.5 microns or more. It was a quality designation popular on US and European jewelry from the 1950s through the 1980s. You'll find HGE stamps on vintage Monet, Napier, and similar estate pieces. The karat number before HGE (like "18K HGE") tells you the gold purity of that layer.

How can I tell if jewelry is real gold or plated?

Check the stamp: solid gold shows only a karat number (585, 750, 14K, 18K). Plated gold shows a karat number plus GP, GF, HGE, or GE. A 925 stamp on a gold-colored piece means it's plated over sterling silver. If there's no stamp at all, it's almost certainly fashion alloy — not precious metal. For physical testing, acid testing kits can confirm gold content without damaging the piece significantly. See: how to tell if jewelry is real gold.

What is the highest quality gold jewelry stamp?

For solid gold: 999 (24K pure gold) is technically the highest purity, but too soft for most jewelry. 750 (18K) is the practical fine jewelry standard — high purity, durable enough for daily wear. For plated jewelry: vermeil is the highest quality stamp — it legally requires 18K gold, a 925 sterling silver base, and minimum 2.5-micron thickness. "18K 925 vermeil" or just "vermeil" from a reputable brand is the best you can buy in the plated category.

Related Guides

• What does 18KGP mean? Value, quality, and durability
• What does HGE mean on jewelry? 18K HGE and 14K HGE explained
• Gold purity numbers: 417, 585, 750 and what they mean
• What does GP mean on jewelry? GP, GF, GE, HGE decoded
• What does 925 mean on jewelry?
• What is gold vermeil?
• Gold filled vs gold plated jewelry
• How to tell if jewelry is real gold

Written by the AJLuxe team — specialists in 18K gold plated sterling silver jewelry. Last updated: June 2026.