18K gold

Gold purity is counted in 24ths, and pure gold is 24K. So 18K gold is 18 parts gold and 6 parts other metals, which is 75% gold and 25% alloy by weight. The other 25% is often copper or silver. In Canada the marks the Competition Bureau lists for 18K are 18K (or another karat spelling), .750 and 750.

Typical recipes show how the colour is built. Yellow 18K is about 15% silver and 10% copper. Rose 18K has about 22% copper. White 18K is 25% palladium, or platinum. They are typical recipes, not the only ones, so two 18K pieces can differ slightly in shade. See yellow gold, rose gold and white gold.

With more gold and less of the metals that shift the colour, 18K tends to read as a deeper, warmer yellow than 14K gold. In typical recipes, the silver share in yellow falls from 30% in 14K to 15% in 18K, and the copper share in rose falls from 32.5% to about 22%, so 18K rose gold is usually a softer pink. Side by side the difference is real but modest, and the exact recipe matters as much as the karat. White gold with more gold and less alloy shows a slight yellow tint unless it is rhodium plated.

Pure gold is soft, and alloying is what gives gold its durability. Higher-karat gold is softer and more prone to scratches and dents. Since 18K has less alloy than 14K, it is generally the softer of the two and shows scratches and wear sooner. Hardness depends on the whole recipe, not the karat alone, so this is a tendency, not a measurement.

18K is suited to daily wear but shows scratches and dents a little sooner than 14K. If the ring will do heavy work with the hands, 14K is the more practical choice; otherwise, choose on colour and gold content. Have the prongs checked from time to time on any karat.

It can be, but the karat does not decide it. Accounts differ on how common nickel is in white gold. The World Gold Council's typical 18K recipes (yellow, rose and white) contain no nickel, and it puts nickel-containing alloys at a small share of white gold alloys. GIA lists nickel among the usual white gold metals, though 18K white gold generally contains less nickel than lower karats, and C. W. Corti notes that many commercial 14K and 18K alloys contain both nickel and palladium.

DermNet NZ advises people with nickel allergy that solid gold of 12 carat or more should be safe, but also says white gold contains nickel. So for white 18K, ask which metals are in the alloy and have it written on the receipt. Palladium-based white gold is the usual nickel-free route. This is general information, not medical advice.

Yes, in one respect. The Precious Metals Marking Regulations treat white gold of 18K or higher as a special case on tolerance (regulations current to September 2026). Where solder is used, the actual gold in an 18K white gold article may fall short of the marked quality by up to 15 parts per 1,000, against 7 parts per 1,000 for other gold. Where no solder is used, the limit is 3 parts per 1,000 for both.

White gold is usually plated with rhodium for a brighter finish, which the rhodium plating entry covers. Marking itself is optional, but a mark that is applied has to be truthful.

Choose 18K when colour and gold content matter most to you. Choose 14K if hard-wearing comes first, or 10K, which has the most alloy of the three. If you are designing a custom piece, note the karat you are leaning towards in the design studio and ask to see 14K and 18K in the same colour before you decide. The custom jewellery design service starts from your idea, and the engagement rings collection is a place to start looking.