Gold Purity and Karats - 24K, 22K, Fineness and Why It Matters for Investors (2026)

Gold purity is measured two ways. Karats divide purity into 24 parts: 24-karat (24K) is essentially pure gold, 22K is 22 parts gold out of 24 (91.67%), and so on. Fineness expresses purity in parts per thousand, such as .9999 (99.99%) or .995 (99.5%). Investment coins and bars are usually described by fineness; jewelry by karats.

For investors, the key point is that purity and gold content aren't the same thing. A 22-karat American Gold Eagle and a 24-karat Gold Buffalo each contain exactly one troy ounce of pure gold in their one-ounce size. The Eagle is simply heavier because of its alloy.

Karats and Fineness Compared

Table: Gold karats, fineness and typical uses | Karat | Gold % | Fineness | Typical use | |---|---|---|---| | 24K | 99.9–99.99% | .999–.9999 | Bullion bars, Buffalos, Maple Leafs | | 22K | 91.67% | .9167 | Gold Eagles, Krugerrands, some jewelry | | 18K | 75% | .750 | Fine jewelry | | 14K | 58.3% | .583 | Jewelry (common in the U.S.) | | 10K | 41.7% | .417 | Lower-cost jewelry |

Purity vs Gold Content

What you're really buying is the amount of pure gold, usually measured in troy ounces. A troy ounce is about 31.1 grams, roughly 10% heavier than the everyday ounce.

Table: Same gold, different purity | Coin | Purity | Total weight | Pure gold | |---|---|---|---| | American Gold Eagle (1 oz) | 91.67% | About 1.09 troy oz | 1 troy oz | | American Gold Buffalo (1 oz) | 99.99% | 1 troy oz | 1 troy oz | | Canadian Gold Maple Leaf (1 oz) | 99.99% | 1 troy oz | 1 troy oz | | South African Krugerrand (1 oz) | 91.67% | About 1.09 troy oz | 1 troy oz |

So a 22K bullion coin isn't "less gold" than a 24K one of the same denomination. The alloy adds durability, not dilution of value. See American Gold Eagle vs Buffalo.

Why Alloy Some Gold?

Pure gold is very soft and scratches easily. Adding small amounts of copper or silver makes coins and jewelry harder and more durable. Copper gives a warmer, redder tone; silver a paler one. Historic coins were often 22K or 90% gold for exactly this reason.

Purity Rules for IRAs

Table: IRS minimum fineness for IRA metals | Metal | Minimum fineness | |---|---| | Gold | .995 (American Gold Eagle permitted by law at .9167) | | Silver | .999 | | Platinum | .9995 | | Palladium | .9995 |

That's why Krugerrands, though popular, aren't IRA-eligible: they're .9167 fine and don't have the statutory exception Gold Eagles enjoy. Jewelry isn't allowed in IRAs at any purity. See IRS-approved gold.

Jewelry vs Bullion as an Investment

Jewelry's price includes design, craftsmanship and retail markup, often well above its gold value, and it usually sells back for little more than its gold content. Lower-karat jewelry contains much less gold per gram. For holding gold's value, bullion coins and bars are far more efficient.

Table: Gold content in 10 grams of different items | Item | Purity | Pure gold in 10 g | |---|---|---| | 24K bar | 99.99% | About 10 g | | 22K coin | 91.67% | About 9.2 g | | 18K jewelry | 75% | 7.5 g | | 14K jewelry | 58.3% | About 5.8 g | | 10K jewelry | 41.7% | About 4.2 g |

Hallmarks and Stamps

Investment bars are usually stamped with the refiner's name or logo, the weight, the fineness and, for larger bars, a serial number. Coins show weight and fineness on the design itself. Jewelry is often stamped with karat markings, such as 14K or 585 for 58.5%. Stamps are helpful but can be faked, so testing and a reputable source still matter.

Which Purity Should Investors Choose?

For investing, purity matters less than the premium you pay per ounce of pure gold and how easily you can resell. A 22K Gold Eagle and a 24K Maple Leaf are both excellent; choose based on price, preference and, for an IRA, eligibility. Lower-karat jewelry and novelty items are poor investments because you pay far more than the gold content is worth. See gold premiums and spreads.

How Purity Is Verified

Reputable mints and refiners stamp fineness and weight on coins and bars. Dealers verify authenticity with precise weight and dimension checks, specific-gravity tests, electronic and ultrasonic testers and, for bars, assay certificates. Buying from established dealers and recognized mints is the simplest protection. See how to buy physical gold.

Gold-Plated and Gold-Filled Items

"Gold-plated" items have a microscopic gold layer over another metal; "gold-filled" items have a thicker bonded layer. Both contain very little gold and have little value as metal. Beware of "commemorative" products sold as investments that turn out to be plated.