Gold bullion is often described as 22 carat, 24 carat, 916.7 or 999.9 fine. These figures all describe purity, but they do not tell you the total amount of gold in an item unless you also check its weight.
Understanding the difference is particularly useful when comparing familiar British gold coins such as Sovereigns and Britannias. A 22-carat coin is not automatically worth less or of lower quality than a 24-carat coin. It simply contains a different proportion of gold and alloying metals.
What Does Carat Mean?
Carat, often abbreviated to ct in the UK, divides gold purity into 24 parts. In simple terms, 24-carat gold is treated as pure gold, while 22-carat gold contains 22 parts gold and two parts other metals.
The same purity can also be expressed as fineness in parts per thousand. Under UK hallmarking standards, 22-carat gold corresponds to 916.6 parts of gold per thousand. You may therefore see 22ct gold described as 916 or 916.7 fine.
Modern 24-carat bullion is commonly marked 999.9, meaning 999.9 parts of gold per thousand. If you would like a fuller explanation of these markings, read our guide to .999 and .9999 fineness.
Why Is 22-Carat Gold Mixed With Other Metals?
Pure gold is relatively soft. Mixing it with a small proportion of other metals creates a harder alloy that can be more resistant to the knocks and wear associated with handling and circulation.
The choice of alloy can also affect colour. Copper can give gold a warmer or redder appearance, while silver can produce a paler yellow. This is why two genuine 22-carat gold coins can look slightly different even when their gold purity is the same.
These differences do not change the stated fineness. A properly specified 22-carat coin still contains approximately 91.67% gold by weight, with the balance made up of its alloy.
Fine Gold Weight and Total Weight Are Different
This is the most important point when comparing 22-carat and 24-carat bullion.
Total weight, sometimes called gross weight, includes every metal in the coin or bar. Fine gold weight counts only the gold. Because a 22-carat item includes more alloying metal, it must have a higher total weight than a 24-carat item if both are designed to contain exactly the same amount of fine gold.
Always check whether a product specification refers to total weight or pure metal content. The word “one ounce” can refer to one troy ounce of fine gold, but you should confirm this from the individual product details rather than relying on the title alone. Our guide to troy ounces and bullion weights explains the measurement in more detail.
The Gold Sovereign: A 22-Carat Example
The British Sovereign is a well-known example of 22-carat gold bullion. The Royal Mint specifies a standard Sovereign at approximately 7.98 grams with a fineness of 916.7.
That 7.98-gram figure is the coin’s total weight, not its fine gold weight. Part of the coin is alloy, so its pure gold content is lower than the gross weight. This is normal for the specification and does not make the coin inferior to a higher-purity product.
Sovereigns were historically designed as circulating coins, and the harder 22-carat alloy suited that purpose. Today, their established specification and long history remain part of their appeal. You can learn more in our guide to Gold Sovereigns in the UK.
The Gold Britannia: A 24-Carat Example
Current one-ounce Gold Britannia bullion coins provide a useful 24-carat comparison. The Royal Mint specifies the 2026 one-ounce Britannia as 999.9 fine gold with a pure metal content of one troy ounce.
Here, the product’s one-ounce description refers to the fine gold content. Although 999.9 gold is commonly called 24 carat, it is better to use the precise fineness shown in the product specification when comparing bullion.
Earlier Gold Britannias were not all made to the same fineness as current issues, so the year matters when buying a pre-owned example. Product specifications should always take priority over assumptions based only on a series name. Our Gold Britannia guide provides further background on the series.
Does 24 Carat Mean Better Than 22 Carat?
Not necessarily. Higher carat means a higher proportion of gold in the metal, but “better” depends on what you are comparing.
A 24-carat product offers very high purity and may be the straightforward choice for buyers who want the greatest proportion of gold within the item. A 22-carat coin can offer greater hardness, an established historic specification and strong recognition among buyers and collectors.
The amount of fine gold, condition, manufacturer or mint, rarity, presentation and market demand can all affect a product’s price. Purity alone does not determine a bullion item’s value or collectability. For a broader format comparison, see gold bars versus gold coins.
What Should You Check Before Buying?
First, check the fineness. A marking such as 916.7 or 999.9 tells you the proportion of gold in the item.
Second, check the total weight and the stated fine gold content. Do not assume they are identical, particularly with 22-carat coins.
Third, confirm the exact year and issue. Specifications can change within a long-running bullion series.
Finally, consider the complete product rather than purity in isolation. Condition, packaging, mintage and whether the item carries a collector premium may all be relevant to the price.
How 156Bullion Verifies Gold Products
Purity markings and published specifications are useful, but they are not a substitute for proper authentication. At 156Bullion, qualifying precious-metal products are professionally authenticated using our Niton Thermo Fisher XRF analyser and Sigma Metalytics Precious Metal Verifier Pro.
These methods provide different forms of information and are used alongside physical checks and product knowledge. No single non-destructive test should be treated as answering every possible authenticity question on its own. Read our detailed article on how XRF testing works for gold and silver.
The Key Difference
Twenty-four-carat gold has a higher proportion of gold, while 22-carat gold includes a larger proportion of alloying metals. That difference affects purity, gross weight, hardness and sometimes colour, but it does not make either format automatically superior.
The clearest comparison comes from checking both fineness and fine gold content. Once those figures are understood, 22-carat Sovereigns and 999.9 Gold Britannias can be compared on their actual specifications rather than on carat alone.
This article is for general information only and does not constitute investment, tax or legal advice.