What Is a Karat? Gold Purity Explained (10k, 14k, 18k, 24k)

A karat measures gold purity on a scale of 24 parts. Pure 24k gold is 99.9 percent gold, 18k is 75 percent, 14k is 58.3 percent, and 10k, the minimum that can legally be sold as gold in the United States, is 41.7 percent. The remainder in each case is other metals, alloyed in for strength and color.

The 24-part scale

The karat system divides purity into twenty-fourths: an item's karat number is simply how many parts out of 24 are gold. The term descends from the carob seeds once used as balance weights in ancient markets, a reminder of how old the problem of measuring gold really is. The arithmetic is always the same. Divide the karat number by 24 and you have the gold fraction: 18 divided by 24 is 0.75, so 18k gold is three-quarters gold by weight.

Common purities and where you meet them

In practice, a handful of standards cover almost everything. 10k gold, 41.7 percent pure, is the durable, affordable end of American jewelry. 14k, at 58.3 percent, is the most common choice in the United States, balancing richness of color with everyday toughness. 18k, at 75 percent, dominates fine jewelry and much of the European market. 22k gold, 91.7 percent pure, appears in traditional Indian and Middle Eastern jewelry and in classic coins like the American Gold Eagle and the British sovereign. 24k, at 99.9 percent or better, is the realm of modern bullion such as the Canadian Maple Leaf.

Why jewelry is rarely pure gold

Pure gold is soft enough to scratch with a coin and bends under daily wear, so jewelers alloy it with harder metals. The additions also set the color. Extra copper produces rose gold. Nickel or palladium bleaches the alloy into white gold, usually finished with a bright rhodium plating that can wear thin over the years. Silver and zinc round out many recipes. Lower karat numbers therefore signal durability and economy rather than inferior craftsmanship; a 14k ring will often outlast an 18k one in daily use. The choice of karat is an engineering decision as much as an economic one, which is why wedding bands and bullion coins sit at opposite ends of the scale.

Reading the hallmarks

Most gold carries a small stamp, usually inside a ring band or on a clasp. Alongside karat marks like 14K you will often find three-digit fineness numbers, which express purity in parts per thousand: 417 corresponds to 10k, 585 to 14k, 750 to 18k, 916 to 22k, and 999 to 24k. European pieces frequently carry only the number. Two cautions apply. Marks like GP, GF, or HGE indicate plated or filled items with very little gold in them, and hallmarks can be counterfeited, so a stamp is a strong hint rather than a guarantee. Professional buyers verify with acid tests or X-ray fluorescence, which reads the metal itself.

Karat versus carat

The two words are pronounced identically and mean different things. Karat with a K measures gold purity. Carat with a C measures gemstone weight, at exactly 0.2 grams per carat. A ring listed as 18k with a one-carat diamond is making two separate claims: about the metal's purity and about the stone's weight. When valuing gold, only the karat matters, and stones are a separate appraisal entirely.

What karat means for value

Purity converts directly into money. Ten grams of 14k gold contains 5.83 grams of pure gold, and that figure, multiplied by the current price per gram, is the metal's melt value. Two chains of identical weight can differ in gold content by nearly half depending on karat, which is why the stamp matters as much as the scale.

Karat also explains why inherited jewelry so often surprises people in both directions. A chunky 10k class ring can hold less gold than a delicate 22k bangle of the same size, because purity and density differ so much. Before assuming anything about a piece's worth, establish both numbers, the weight and the karat, and only then look up the price.

If you have a drawer of mixed karats and want to know what it all adds up to, you can get a live estimate at today's prices at offrampgold.com.