Understanding Gold Purity: 9ct to 24ct

When buying or selling jewellery, one of the most important factors to understand is gold purity.

The carat number (often written as “ct”) shows the proportion of pure gold within a piece. Gold is measured in 24 parts:

24ct gold = 24 out of 24 parts gold (99.9% pure)
18ct gold = 18 out of 24 parts gold (75% pure)
9ct gold = 9 out of 24 parts gold (37.5% pure)

In simple terms, the higher the carat, the greater the gold purity. Because gold itself carries intrinsic value, higher purity generally means higher underlying value.

When selling scrap gold, this becomes particularly relevant. A higher carat piece will usually achieve a higher price because it contains a greater proportion of pure gold.

Common UK Carats

In the UK, the most common gold purities found in jewellery are:

9ct (37.5% gold)
14ct (58.5% gold)
18ct (75% gold)
22ct (91.6% gold)
24ct (99.9% gold)

9ct and 18ct are particularly common in British jewellery. 22ct and 24ct are higher purities and contain a much larger proportion of gold.

Most modern pieces are stamped with their carat to indicate gold purity. However, some older, inherited or imported items may not carry a clear stamp. Over time, hallmarks can also become worn and difficult to read.

Purity and Value

When selling scrap gold, value is determined by two key factors:

The weight of the item
The gold purity (carat)

Two pieces that appear identical in size can have very different values if their gold purity differs. For example, an 18ct item contains significantly more pure gold than a 9ct piece of the same weight.

Understanding gold purity helps sellers set realistic expectations before receiving a valuation. The higher the purity and the heavier the item, the more gold content it contains - and therefore the higher the potential return.

Finding Hallmarks

In the UK, hallmarks are used to confirm both authenticity and gold purity. These small stamped markings indicate the carat and are regulated to protect buyers and sellers.

Common UK hallmark numbers include:

375 (9ct)
585 (14ct)
750 (18ct)
916 (22ct)
999 (24ct)

Hallmarks are typically found:

Inside ring bands
On necklace or bracelet clasps
On the inner surface of bangles

Over the years of wear, these markings may fade. Some pieces, particularly very old items, may not have a visible hallmark at all. In such cases, professional testing is required to determine gold purity accurately.

Professional Testing

A professional evaluation ensures accuracy and removes uncertainty.

At Sharps Pixley, gold purity is tested using advanced, non-destructive methods to determine precise composition and weight. This guarantees that sellers receive a fair valuation based on live market pricing and the true gold content of their items.

Professional testing is particularly important for unmarked, damaged or inherited pieces where purity may not be immediately clear.

Tips for Sellers

If you are considering selling scrap gold:

Check for a visible hallmark and note the carat
Remember that small, broken or single items still contain gold
Do not assume unmarked items are low value
Understand that higher gold purity typically means a higher payout

Most importantly, seek a professional valuation for certainty. Knowing the gold purity of your items helps you understand what to expect, but expert testing ensures you receive an accurate and fair price.

If you are ready to sell scrap gold, contact Sharps Pixley or visit our London showroom for a secure, transparent and professional assessment.

07 Oct 2026 | Categories: Gold, Beginner's guide, Selling gold