Gold Purity Karats Explained: 24k, 18k, 585, 750

What karats measure in gold

When you look at gold jewelry or coins, you’ll often see a karat number. That number shows how much of the item’s metal is pure gold, out of 24 total parts. 24 karat means all of it is gold, nothing else. So if you see something marked 18 karat, it means 18 out of 24 parts are gold, the other 6 parts are made up of other metals like copper, silver or sometimes zinc or nickel. That’s 75 percent gold content.

The extra metals (these are called alloys) make gold tougher and they can also change its shade. If you tried to wear a pure gold ring every day, you’d find it bends or scratches easily; jewelers make things in lower karat gold so they last longer. Remember, the karat mark tells you only about the purity, not the piece’s weight or value. A light piece and a heavy piece with the same karat mark don’t have the same gold content.

How fineness and hallmarks show purity

Some countries use something called ‘fineness’ instead of karats. Fineness tells you the gold percentage as a number out of 1,000. For example, a ‘750’ stamp means 750 parts gold out of 1,000, or 75 percent gold, it matches 18 karat exactly. Other usual marks you’ll see are 999 or 999.9 (very close to pure), 916 (22 karat), and 585 (about 14 karat).

A hallmark is a stamp applied by an authorized body, often an assay office, to verify purity or sometimes certify who made the item. Whether hallmarking is mandatory or voluntary changes with each country. Some places stamp every piece, some stamp nothing. While a hallmark adds reassurance, fake or misapplied stamps do exist, so double check purity if you need confirmation for a sale or insurance.

Comparing common gold purities and values

24 karat: marked 999 or 999.9, purest form available
22 karat: often marked 916, contains about 91.6 percent gold
18 karat: stamped 750, 75 percent gold
14 karat: labeled 585, about 58.5 percent gold
9 karat: stamped 375, meaning 37.5 percent gold

The actual gold content is the item’s weight multiplied by its purity. So, a 10 gram ring in 18 karat gold would hold about 7.5 grams of real gold. If you ever want to sell, buyers usually quote prices for the pure gold content only. There’s a step-by-step at how scrap gold is valued, if you want details.

Market prices for gold are unpredictable, they don’t only rise. If you want to check today’s value, you can use our gold price per gram calculation for a current estimate.

Frequently asked questions

What does 18k gold mean?

18k gold is three quarters pure gold, 18 parts out of 24 are gold, the other 6 are metals chosen for strength and color. When you see ‘750’ stamped on an item, it also means 18 karat.

Is 14k or 18k gold better?

There’s no single answer. 18k gold has more gold in it and is softer, while 14k gold is harder and more scratch-resistant. What’s best for you depends on how you’ll wear it, which color you like, and what you want to pay. Purity matters, but resale value also depends on thing's weight and how the buyer prices it.