What Does 375 Mean on Jewelry? (9K Gold Hallmark Explained)

You found a stamp that reads "375" on a piece of jewelry and you're wondering what it means. The answer is straightforward: 375 is the international hallmark for 9-karat gold. It tells you the metal contains 375 parts per 1,000 pure gold — 37.5% by weight.

In the karat system, 37.5% gold is called 9-karat gold (9K or 9CT). 375 and 9K are two different ways to express identical gold purity. The difference is only which country's stamping system was used.

What Does 375 Mean on Jewelry?

The 375 stamp is a millesimal fineness mark. It means 375 out of every 1,000 parts in the metal are pure gold. The remaining 62.5% is alloying metals — typically copper, silver, zinc, or palladium depending on the desired color (yellow, white, or rose gold).

The karat equivalent is 9K: if you divide 24 equal parts of metal and 9 of those parts are pure gold, you have 9-karat gold. Here's the comparison:

Where Is 375 Gold Most Common?

9-karat gold (375) is the most common everyday gold jewelry in the United Kingdom, Ireland, Australia, and much of the Commonwealth. It holds a particular place in British jewelry culture: historically, 9K was the standard mass-market gold that made genuine gold jewelry accessible to a broad population. British high street jewelers — Argos, H.Samuel, Ernest Jones — have sold 9K gold as their standard entry-level gold for decades.

In the United States, 9K gold cannot legally be sold as "gold jewelry" — the US minimum is 10K (417). You won't typically find 375 stamps on new American-made pieces, though imported UK pieces and antique jewelry may carry it.

Is 375 Gold Real Gold?

Yes — 375 is genuine solid gold. It contains 37.5% pure gold by weight and carries real monetary value. The high proportion of alloying metals does not make it fake or inferior — it makes it harder and more affordable. The piece is solid gold throughout, not plated or filled.

For comparison: a 5-gram 375 gold ring contains approximately 1.875 grams of pure gold. At current gold prices (~$3,300/troy oz), that's roughly $200 in gold content. A solid 375 ring is not costume jewelry — it's a real precious metal piece.

375 vs 585 vs 750: What's the Difference?

One important note: the higher copper content in 375 gold can cause skin reactions in people sensitive to copper. This is rare, but if you've had reactions to lower-karat gold before, a 14K (585) or 18K (750) piece may be more comfortable for sensitive-skin wearers.

Does 375 Gold Tarnish?

Pure gold doesn't tarnish — it's chemically inert. But 375 gold contains 62.5% other metals, primarily copper. Over time, those alloying metals can react with moisture, skin acids, and air to cause slight surface dulling or patina. This is more noticeable on 9K than on higher-karat pieces with more gold content.

Regular polishing with a soft cloth and keeping the piece away from harsh chemicals (chlorine, bleach, saltwater) prevents most surface changes. Genuine 375 gold does not corrode — any surface change is cosmetic and easily polished away.

How to Tell If 375 Is Genuine

The same verification methods apply as for any gold hallmark:

• Acid test: 9K testing acid will not dissolve genuine 375 gold
• XRF test: a jeweler's XRF analyzer reads the exact metal composition non-destructively in under a minute
• UK assay marks: British-made 9K gold carries government assay office marks (crown symbol + 375, plus maker and date marks in traditional British hallmarking) — these are difficult to fake and add authenticity
• Weight: gold is dense; if a piece feels very lightweight for its size, verify before assuming it's solid gold

Is 375 Gold Worth Buying?

For the right buyer, yes. 375 gold offers the lowest entry price into genuine solid gold jewelry. It wears well, holds its shape, and has real resale value. For pieces with sentimental significance or for buyers on a budget who want real gold over gold-plated, 9K is a legitimate choice.

The trade-off: the pale color, potential for slight tarnishing on the high-copper alloy, and slightly higher skin-reaction risk compared to 14K or 18K. For pieces worn against the skin constantly (like engagement rings), consider whether a step up to 585 is worth the extra cost for the lower alloy content and better color saturation.

Final Thoughts

The 375 stamp is straightforward once you know the system. It means 9 karat gold — 37.5% pure gold in a durable alloy used widely across the UK, Australia, and Commonwealth countries.

It's real gold. It has real value. And for buyers who want solid gold jewelry at a lower price point, 9K is a completely legitimate choice. The trade-off is less richness in color compared to 14K or 18K, and potential sensitivity for those with nickel allergies.

If you're evaluating a piece stamped 375, you can be confident it's not plated or fake — it's a solid gold alloy that will last decades with normal care. Just compare it honestly against 585 (14K) and 750 (18K) if you're considering an upgrade in purity.

Written by Vaishakhi Ajmera, founder of AJLuxe. Last updated: June 2026.

Explore more: Complete Gold Jewelry Guide