375 / 9K Gold — What This Hallmark Means

A "375" stamp means the jewelry is made from 9-karat gold, containing 37.5% pure gold and 62.5% other alloying metals. In the karat system, 9 out of 24 parts are pure gold. While this is a lower gold content than 14K or 18K, 9K gold is still genuine gold and is particularly popular in the United Kingdom, Australia, and New Zealand, where it is the minimum legal standard for items to be sold as gold.

The high proportion of alloying metals in 9K gold gives it exceptional hardness and durability — it's significantly more resistant to scratches and dents than higher-karat golds. This makes 9K gold an excellent practical choice for everyday jewelry that sees heavy wear. However, the lower gold content means the color tends to be paler and less saturated than 18K or even 14K gold.

9K gold is also considerably more affordable than higher-karat options, making it accessible for a wider range of budgets. In the UK market, it accounts for a significant portion of all gold jewelry sold, particularly in the fashion and everyday jewelry segments.

The 375 mark follows the same placement conventions as other gold marks — inside ring bands, on clasps, on tags near closures, and on earring posts or backs. In the UK, the 375 mark is part of a broader hallmarking system and is typically accompanied by an assay office mark, a date letter, and often a maker's mark.

In Australia and New Zealand, you may see "9K," "9CT," or "375" used interchangeably. Some British jewelry features the crown symbol alongside 375 as part of the official hallmark.

Variations include "375," "9K," "9KT," "9CT," and ".375." In the UK's hallmarking system, the gold purity is indicated by a crown symbol followed by the number 375. Scottish pieces hallmarked at the Edinburgh assay office will show a thistle rather than a crown.

Some pieces may also show "9C" (9 carat) or simply bear the full UK hallmark without a separate numerical purity stamp. Antique and vintage British pieces may use older hallmarking conventions that look different from modern stamps.

A common misconception is that 9K gold is "fake" gold or not real gold. This is incorrect — 9K gold contains genuine gold and meets the legal standards in many countries. It simply contains a lower percentage of gold than higher-karat options. In the US, the minimum legal standard for gold is 10K, which leads some Americans to incorrectly dismiss 9K gold.

Another myth is that 9K gold tarnishes like silver. While 9K gold can occasionally develop a slight dulling due to its higher base metal content, it doesn't tarnish in the same way silver does. Regular cleaning will keep it looking bright and attractive.

If your piece is marked 375 or 9K, you have a durable and genuine gold item. It's particularly well-suited for everyday wear due to its hardness. To verify authenticity, a jeweler can perform standard gold testing procedures.

Clean 9K gold with warm soapy water and a soft cloth. Its hardness means it can tolerate slightly more vigorous cleaning than higher-karat gold, but you should still avoid harsh chemicals and abrasive materials. If you're in the UK, you can verify the hallmark through the Birmingham, London, Edinburgh, or Sheffield assay offices.