Gold Hallmarks and Stamps: What 417, 585, 750 and GF Mean

There are two ways to stamp gold purity. The karat system divides gold into 24 parts. The millesimal system (also called fineness) gives parts per thousand. They describe the same thing.

Karat stamp	Millesimal stamp	Pure gold content	Common use
9K	375	37.5%	UK and Europe; rare in US stores
10K	417	41.7%	US chains, rings and everyday pieces
14K	585	58.3% (stamp rounds to 58.5%)	The US standard for fine jewelry
18K	750	75%	Fine jewelry, luxury watches
22K	916	91.6%	South Asian and Middle Eastern jewelry
24K	999 or 9999	99.9% or more	Bullion, some Asian jewelry

The 585 stamp is a slight round-up: 14 divided by 24 is 58.33%, and 585 became the trade standard so that alloys land safely above the legal minimum. You may also see platinum stamped 950 or PLAT, and sterling silver stamped 925 or STER.

For what each karat means for wear, color and price, see the gold karat guide.

Which one you see depends mostly on where the piece was made.

• US-made pieces usually carry the karat mark: 10K, 14K, 18K, sometimes written 14KT or 14KP. KP stands for "karat plumb," an older US mark meaning the alloy is at least the full stated karat.
• Italian and European pieces usually use numbers: 375, 585, 750. Italian pieces often add a star-shaped maker's mark with a number and province code.
• Many modern pieces carry both, for example "14K 585."

Do not confuse karat (K, gold purity) with carat (ct, diamond weight). A chain stamped "10K" says nothing about diamonds. More on that in carat vs karat.

Two sets of rules govern gold marks in the US.

The National Gold and Silver Stamping Act sets the legal tolerance. A piece stamped 14K must assay within 3 parts per thousand of 14K if it has no solder, or within 7 parts per thousand counting solder. So a 14K piece cannot test meaningfully below 58.3%.

The FTC Jewelry Guides (16 CFR Part 23) say it is deceptive to misrepresent gold content. In the 2018 revision the FTC dropped the old 10K floor for using the word "gold," but kept the requirement that the karat be disclosed accurately. They also say hollow gold pieces should not be marked or described as "solid," and should disclose the hollow center near the word gold.

The Stamping Act also expects a piece carrying a gold quality mark to carry a trademark (the maker's or seller's mark) next to it, so there is someone accountable for the claim.

A maker's mark is a logo, initials or registered trademark stamped next to the purity mark. It tells you who stands behind the stamp.

• Present and clean: a good sign. Look the mark up; many US trademarks can be searched in public databases.
• Missing on a newer piece: not proof of fake, since some imports and repairs lose it, but a reason to test the metal.
• Mismatched style: a crisp, deep karat stamp next to a shallow, sloppy logo can mean one was added later.

Antique and estate pieces may also carry hallmarks from national assay offices, like the UK's Assay Office marks, which include a fineness mark, an office symbol and a date letter. Those are among the most reliable marks in the world because an independent office tested the metal before stamping it.

These letters mean the piece is not solid gold. The FTC Guides define what each term should mean:

Stamp	Means	FTC standard
GF, 1/20 14K GF	Gold filled	Karat gold layer of at least 10K, mechanically bonded, weighing at least 1/20 of the total metal
RGP, 1/40 12K RGP	Rolled gold plate	Mechanically bonded layer of at least 1/40 of total metal weight
GO	Gold overlay	Same 1/40 standard as rolled gold plate
GEP, GE	Gold electroplate	At least 10K gold, at least 0.175 microns thick
HGE, HGEP	Heavy gold electroplate	At least 10K gold, at least 2.5 microns thick
GP	Gold plate	Under FTC terms a mechanically bonded layer of at least 1/40 of the metal weight; in practice many cheap pieces stamped GP carry a thin electroplate
Vermeil	Gold over sterling silver	At least 10K gold, at least 2.5 microns, over a sterling silver base

The trap: "14K HGE" or "18K GP" leads with a karat number. The karat describes the thin layer, not the piece. Read every letter after the number. For how long each type lasts in real wear, see plated vs filled vs solid gold.

Stamps are small, usually 1 to 2 mm tall. Use a phone camera on max zoom or a 10x loupe.

Piece	Where to look
Chains and bracelets	On the clasp, the tongue of a box clasp, or a small tag or link next to the clasp
Rings	Inside the band, at the bottom of the shank
Earrings	On the post, the back, or inside a hoop near the hinge
Pendants	On the back of the pendant or on the bail (the loop the chain passes through)
Watches	Inside the caseback and on the bracelet clasp

Plain gold chains in our catalog, like the Miami Cuban Chain 5mm ($4,260) and the Franco Chain 3mm ($3,425), are 10K gold, and a 10K piece is marked 10K or 417. A worn stamp on an old chain is normal; heavy wear around the clasp can rub a stamp nearly flat over the years.

Gold is not the only metal with a code. If you are sorting a jewelry box, these are the stamps you will run into most.

Stamp	Metal	Content	Note
925, STER, Sterling	Sterling silver	92.5% silver	Tarnishes; the base metal of vermeil
800	Silver	80% silver	Common on older European pieces
950, PLAT, PT950	Platinum	95% platinum	Heavy, naturally white
900, PT900	Platinum	90% platinum	Common in Japan
PD, 950 PD	Palladium	95% palladium	Lighter white precious metal
SS, 316L, Stainless	Stainless steel	Steel alloy	No precious metal value

Two-tone and tri-color pieces carry a single karat stamp because all the colors are the same karat. A "10K two-tone" pendant is 10K yellow and 10K white gold together, not a mix of gold and plated metal. Our Mixed Natural Diamond Pendant, 10K Two-Tone Gold ($9,500) is an example of that construction.

Heavy chains are the most copied pieces in jewelry, so the stamp on a Cuban link deserves a careful look.

• Box clasps: the stamp is usually on the tongue that slides into the clasp, or on the side of the box. Look at both.
• Lobster clasps: check the small tag or the end link next to the clasp. Stamping the lobster itself is less common because the part is small.
• Hollow chains: a hollow chain should be disclosed as hollow. Pick it up; a hollow Cuban is far lighter than a solid one of the same width.
• Italian chains: look for the purity number (375, 585, 750) plus a star-shaped maker's mark with a number and province letters.
• Every link the same: on a real chain the links are uniform in color, including inside each link where plating would thin first.

A clean stamp, a weight that makes sense for the width and length, and an XRF reading that matches the stamp are the three things that, together, prove a chain. One of them alone is not enough.

Stamps are often several marks in a row. Read them left to right and make sure they agree with each other.

Stamp line	What it says
14K + logo	Solid 14K gold, with the maker's trademark beside it
585 + star + 1234 AR	14K gold, Italian maker number 1234 from the Arezzo province
10K 417	Solid 10K gold, marked both ways
14K HGE	Heavy gold electroplate; the 14K describes only the plating
1/20 14K GF	Gold filled with a 14K layer weighing 1/20 of the metal
925 14K	Sterling silver, often gold plated; check whether the listing says vermeil
PT950	Platinum, 95% pure

Two marks that contradict each other, like "14K 925," always mean a silver piece with gold on top. A solid gold piece never needs a silver mark.

A stamp is a claim, not proof. Counterfeiters stamp "14K" on plated brass, and some sellers stamp a higher karat than the alloy really is. Warning signs:

• Color wearing through at the clasp or edges, showing a pink, gray or silver metal underneath.
• Strong magnet pull. Gold is not magnetic. A clasp spring may react slightly, but the links should not.
• Too light for its size. A wide chain that feels like aluminum is either hollow or not gold.
• Green or black marks on skin after a day of wear, from copper or nickel in a base metal.
• A price far below the gold value. Gold has a daily market price; nobody sells it at half.

Home checks only screen. The reliable test is an XRF (X-ray fluorescence) reading at a jeweler, which measures the metals in seconds without damaging the piece. Acid testing works too but scratches the surface. Full walkthroughs: how to tell if gold is real and how to tell if a Cuban link is real. If skin discoloration is your issue, read why jewelry turns skin green.