Jewelry Hallmarks and Quality Marks: How to Read Them

A quality mark states a piece’s metal and purity, such as “14K,” “750” or “925.” In the United States the manufacturer or importer applies that mark, and federal law requires a trademark (registered or applied for) or the maker’s name beside any gold or silver quality mark. In the UK, a hallmark is applied only by an independent assay office after testing, and it is compulsory for most precious metal articles above a set weight.

The US system

Quality marks and the trademark rule

In the US, quality marks are applied by manufacturers and importers, and two sets of rules govern them: the National Gold and Silver Stamping Act, and the FTC Jewelry Guides. This is a summary, not legal advice.

• Accuracy within tolerance. A gold or silver mark must not overstate the fineness beyond the tolerances set by the Stamping Act. Gold tolerances are explained in Gold Karats Explained and silver tolerances in 925 Sterling Silver.
• Trademark beside the mark. Under 15 U.S.C. 297(b), anyone who applies a quality mark indicating gold or silver, or imports such an article, must also apply a trademark that has been registered or applied for registration in the US, or the person’s name. The trademark must be applied by the same method as the quality mark, in lettering at least as large, and as close as possible to it. A stamp such as “14K” with no maker’s mark nearby is a warning sign on US goods.
• Plated goods. The same section bars karat marks on plated articles unless words such as “gold plate” or “gold filled” go with them, and bars “sterling” and “coin” on plated articles altogether.
• FTC wording. 16 CFR 23.3 requires karat gold to be marked with its karat, such as “14K” or “14 Kt.,” and 16 CFR 23.6 sets the platinum marks and the accepted abbreviations: “Pt.” or “Plat.” for platinum and “Pd.” or “Pall.” for palladium.

The trademark requirement in the Stamping Act covers gold and silver. Platinum marking in the US is set out in the FTC Guides, as described in Platinum in Jewelry.

The UK system

When a hallmark is required

According to the Hallmarking Guidance Notes published by the four UK assay offices, the main offence under the Hallmarking Act 1973 is about description. In the course of trade it is an offence to describe an unhallmarked article as wholly or partly platinum, gold, palladium or silver, or to supply one so described. The rule applies to online sellers, market stalls and shops alike, and to pre-owned as well as new pieces.

Articles below these weights are exempt:

Metal	Exemption weight
Platinum	0.5 g
Gold	1.0 g
Palladium	1.0 g
Silver	7.78 g

Where an article contains more than one precious metal, the threshold of the most precious metal applies. Items proved to be of minimum fineness and made before 1950 may be sold without a hallmark.

What a UK hallmark contains

A UK hallmark has three compulsory marks:

1. Sponsor’s mark. The maker or sponsor, shown as at least two letters within a surround. No two sponsor’s marks at the same assay office are alike.
2. Metal and fineness mark. The fineness as a number in parts per thousand, with the shape of the surround showing the metal.
3. Assay office mark. The office that tested and marked the piece: London, Edinburgh, Birmingham or Sheffield.

Optional marks may be added on request: traditional fineness symbols for sterling, Britannia silver, gold, platinum and palladium, and a date letter. The date letter was compulsory until 1999, and it changes every 1 January.

The legal UK standards are 999, 950, 900 and 850 for platinum; 999, 990, 916.6, 750, 585 and 375 for gold; 999, 950 and 500 for palladium; and 999, 958, 925 and 800 for silver. Retailers must also display a Dealer’s Notice explaining hallmarks, as Trading Standards reminds buyers.

International Convention marks

The UK has signed the International Convention on Hallmarks since 1972. An article carrying a Convention hallmark is legally recognized in all member countries without retesting. A Convention hallmark has four parts: a sponsor’s mark, the Common Control Mark (CCM), a fineness mark and an assay office mark. The CCM shows a pair of scales. In one type, the fineness is built into the design and the outline shows the metal; in the other, the scales are the same for every metal and a separate mark gives the metal and fineness. The UK guidance lists the Convention finenesses as 850, 900, 950 and 999 for platinum; 375, 585, 750, 916, 990 and 999 for gold; 500, 950 and 999 for palladium; and 800, 925, 958 and 999 for silver.

Common stamps and what they mean

Stamp	Meaning
999	Fine (24K) gold, fine silver, or pure platinum or palladium, depending on the metal
916	22K gold
750	18K gold
585	14K gold
417	10K gold
375	9K gold
925	Sterling silver
958	Britannia silver
PT950, 950Pt., 950Plat.	Platinum, 950 parts per thousand
900Pt., 850Pt.	Platinum, 900 or 850 parts per thousand
PD950, 950Pd.	Palladium, 950 parts per thousand
GF, 1/20 14K GF	Gold filled: karat gold at least 1/20 of the metal weight
RGP	Rolled gold plate: at least 1/40 of the metal weight
GEP, G.E.P.	Gold electroplate: at least 0.175 microns of fine gold equivalent
GP	Gold plate: either electroplate or a mechanically applied layer of at least 1/40 of the metal weight
HGE	Heavy gold electroplate: at least 2.5 microns of fine gold equivalent
Vermeil	Gold of at least 10K, at least 2.5 microns, over sterling silver

The plating figures are the FTC minimums. They are explained in Gold Plated vs Gold Filled vs Vermeil, and palladium’s properties are in Palladium in Jewelry.

How to look at a mark with a loupe

A 10x loupe is the standard magnifier in gemology, according to GIA, and it is enough to read most marks.

1. Find the marks. Common places are inside a ring shank, on a clasp or its tongue, on a jump ring near the clasp, on an earring post or on the back of a pendant bail.
2. Get good light. Work under a bright lamp or near a window, and clean the area first if it is dirty.
3. Hold the loupe close to the eye, then bring the piece toward the loupe until the mark is sharp. Bracing both hands together keeps the image steady.
4. Read every part. Note the number or karat, any metal symbol or abbreviation, and any maker’s mark beside it. On UK pieces, look for the three compulsory marks together.
5. Check the quality of the strike. A blurred, shallow or crooked mark is not proof of a fake, since marks wear, but it is a reason to look harder.

Fake and misleading stamps

A stamp is a claim, not a test. The UK assay offices point out that it is not possible to detect the precious metal content of an item by sight or touch, which is why the UK requires independent testing. In a 2019 notice, Trading Standards estimated that around 150,000 items of fake “gold” jewelry could be listed for sale in the UK each year, and reported counterfeit copies of designer-branded pieces.

Practical cautions:

• A lone fineness number is not a hallmark. In the UK, a silver article of 7.78 g or more needs the full hallmark; a “925” stamp alone is only acceptable on underweight articles.
• Missing maker’s marks on US gold or silver pieces fall short of the Stamping Act’s trademark requirement.
• Mixed messages, such as “925” on a piece that is clearly plated base metal, or “18K” with “GP” in small letters, deserve a second look.
• Testing settles it. When value matters, ask a jeweler to test the metal or, in the UK, use an assay office.

Trading Standards advises buying only from reputable sources that comply with the Hallmarking Act, checking the hallmark and reading the Dealer’s Notice.

Common questions

Does “14K” on a ring guarantee it is gold? No. In the US it is the maker’s or importer’s claim, backed by legal liability rather than independent testing. A trademark next to it at least identifies who made the claim.

Is a UK hallmark recognized abroad? A Convention hallmark, with the Common Control Mark, is recognized in all member countries of the International Convention on Hallmarks without retesting.

What does a date letter tell me? It shows the year the piece was hallmarked in the UK. It has been optional since 1999, so modern pieces may not have one.