What does 'carat' actually mean?
When people talk about the "carat" of gold, they're really talking about its purity. Pure gold is soft, so it's almost always mixed with other metals such as copper, silver, zinc or palladium to make it harder and more practical for jewellery. The carat figure (written as "ct" or sometimes "K") tells you how much of the piece is genuine gold.
The scale runs to 24. So 24ct is as close to pure gold as you'll find, while 9ct contains a smaller proportion of gold and more of those other metals. In the UK you'll also see a three-digit "fineness" number stamped on hallmarked items, which says the same thing in parts per thousand.
Here's how the common grades line up:
- 9ct gold = 375 fineness (37.5% gold)
- 14ct gold = 585 fineness (58.5% gold)
- 18ct gold = 750 fineness (75% gold)
- 22ct gold = 916 fineness (91.6% gold)
- 24ct gold = 999 fineness (99.9% gold)
If you look closely at a ring or chain, the tiny stamp showing one of these numbers is part of the official UK hallmark. It's a reliable, independent indicator of what you actually own.
How the grades compare
9ct gold (375)
9ct is the most common gold sold in the UK, especially for everyday rings, chains and earrings. Because it's only just over a third gold, it's harder-wearing and more affordable. The trade-off is that it can look a little paler and, over many years, may be more prone to tarnishing than higher grades.
14ct gold (585)
14ct sits in the middle and is hugely popular in the United States, though less common in British high-street jewellery. It offers a good balance of durability and a slightly richer colour than 9ct, which is why you'll sometimes see it on imported or designer pieces.
18ct gold (750)
18ct is three-quarters pure gold and is widely regarded as the sweet spot for fine jewellery. It has a warm, rich colour and a quality feel, while still being durable enough for rings and bracelets. Many engagement and wedding rings, as well as higher-end watches, use 18ct.
22ct gold (916)
22ct has a deep, vivid yellow colour and is traditional in much South Asian and Middle Eastern jewellery. It's prized for its richness and high gold content, but it's noticeably softer, so it can scratch and bend more easily with daily wear.
24ct gold (999)
24ct is essentially pure gold. It has an unmistakable bright colour but is very soft, which makes it impractical for most jewellery you'd wear every day. It's more often seen in coins, bars and investment pieces than in rings or chains.
Why higher carat isn't always 'better'
It's tempting to assume that a higher number is automatically better, but that depends entirely on what you need.
Pure gold is beautiful, yet its softness is a genuine drawback for jewellery that takes knocks, such as a wedding ring worn daily. A 9ct or 18ct piece will generally resist scratches and dents far better than 22ct or 24ct. So "better" really comes down to use: investment buyers often favour high purity, while many people choosing everyday jewellery sensibly prefer a lower carat that holds up to real life.
Colour is also a matter of taste rather than quality. Some people love the deep yellow of 22ct; others prefer the subtler tone of 9ct or the warmth of 18ct. None is "wrong".
How purity affects resale value
This is the part worth understanding clearly. When you sell gold for its metal value, purity is the single biggest factor in what it's worth. A piece that is 75% gold (18ct) contains far more actual gold per gram than one that is 37.5% gold (9ct), so for the same weight it will be worth considerably more.
The value of any item generally comes down to three things: its weight, its carat (purity), and the gold price on the day, which moves constantly. That's why no honest buyer can quote an exact figure sight unseen, and why genuine offers are always given as a range or worked out from those details rather than promised in advance.
A few practical points worth keeping in mind:
- Check for the hallmark. It confirms the carat and reassures any buyer.
- Weigh things together by carat. Mixing grades makes a fair assessment harder.
- Remember that designer or antique pieces may be worth more intact than melted, so it's worth asking before selling anything unusual.
None of this is financial advice, and gold prices can fall as well as rise. It's simply the mechanics of how value is calculated.
A quick recap
Carat is a measure of purity, from 9ct (375) up to 24ct (999). Lower carats are harder and more practical for everyday wear; higher carats are purer, richer in colour and softer. For resale, purity and weight, combined with the day's gold price, drive the value.
If you're weighing up what your jewellery might be worth, it can help to remember that the figures above are only ever a starting point. When you're ready, a reputable local buyer in your area can usually offer a free, no-obligation valuation so you can make an informed decision in your own time.