Which Karat of Gold Is Best for Investing?
TL;DR: For pure bullion investment, 24-karat gold, .999 to .9999 fine, is the standard, the purity behind coins like the American Gold Buffalo and the Canadian Gold Maple Leaf. 22-karat gold, .9167 fine, is also bullion-grade and more scratch-resistant, the durable alloy used in the American Gold Eagle and the South African Krugerrand. 14-karat and 18-karat gold are jewelry alloys, not investment-grade bullion. A gold IRA adds its own legal floor, a minimum .995 fineness under IRC § 408(m)(3), though the Eagle clears that hurdle through a separate named-coin exception rather than its actual purity.
The Short Answer: 24-Karat Gold Is the Bullion Standard
For an investor buying gold purely as bullion, 24-karat gold at .999 to .9999 fine is the standard, and 22-karat gold at .9167 fine is the accepted bullion-grade alternative, prized for durability. 18-karat and 14-karat gold are jewelry alloys and are not considered investment-grade.
Karat and fineness describe the same thing from two different traditions. Karat measures purity out of 24 parts, so 24-karat gold is 24 parts pure gold out of 24. Fineness, sometimes called millesimal fineness, measures purity out of 1,000 parts, so a bar marked .9999 is 999.9 parts pure gold out of 1,000. Both systems converge on the same idea: how much of a piece of metal is actual gold versus another metal mixed in to change its properties.
Investment-grade bullion sits at the top of that purity range. The two purity levels that dominate the coin and bar market for pure investment purposes are 24-karat and 22-karat, the standards behind nearly every widely traded bullion coin and bar sold by refiners and mints. Everything below that range, principally 18-karat and 14-karat gold, belongs to the jewelry market, where durability and workability matter more than raw purity.
How Karat Converts to Fineness
Karat and fineness convert directly through simple division: divide the karat number by 24 to get the fineness. 24-karat gold is 24 divided by 24, or .999 to .9999 fine. 22-karat gold is 22 divided by 24, or .9167 fine. 18-karat gold is .750 fine, and 14-karat gold is .5833 fine.
The table below lines up the four karat levels an investor is likely to encounter, with the fineness each converts to and where each purity level actually gets used in the market.
| Karat | Fineness | Percent Pure Gold | Typical Use |
| 24k | .999 to .9999 | 99.9% to 99.99% | Bullion coins and bars |
| 22k | .9167 | 91.67% | Bullion-grade coins built for durability |
| 18k | .750 | 75.0% | Fine jewelry |
| 14k | .5833 | 58.33% | Everyday jewelry |
The gap between 24-karat and 18-karat is larger than it looks on paper. An 18-karat piece is a quarter alloy by weight, copper, silver, or other base metals mixed in to change color and hardness. That alloy content is exactly what makes 18-karat and 14-karat gold suitable for rings and bracelets that need to survive daily wear, and exactly why neither is priced or traded as investment bullion. A dealer or refiner selling bullion for its metal content, not its craftsmanship, prices almost exclusively in 24-karat or 22-karat product.
24-Karat Gold: The Purest Bullion on the Market
24-karat gold, .999 to .9999 fine, is the purest form of bullion sold to investors, and it is the standard behind most of the world’s best-known investment coins and bars.
The U.S. Mint describes the American Gold Buffalo as “the first .9999 fine 24-karat gold coins ever struck by the Mint,” a 1-ounce coin introduced in 2006. The Canadian Gold Maple Leaf, produced by the Royal Canadian Mint, was the first bullion coin to reach that same .9999 standard back in 1979, and some special issues go further still, to .99999, or “five nines.” The Austrian Gold Philharmonic, struck by the Austrian Mint, carries “the highest possible fineness of 999.9,” and the Australian Gold Kangaroo from the Perth Mint is struck from “1oz of 99.99% pure gold.” Gold bars from accredited refiners follow the same convention, and the London Bullion Market Association sets its own Good Delivery standard at a minimum acceptable fineness of 995.0 parts per thousand, the floor for a bar to trade as institutional-grade gold at all.
For an investor whose only goal is owning the most gold content per unit weight, with the least alloy along for the ride, 24-karat product is the cleanest way to do it. The trade-off is softness. Pure gold is a soft metal, more prone to nicks, scratches, and edge wear in handling and storage than an alloyed coin, which is part of why some of the most widely held bullion coins in the world are not 24-karat at all.
22-Karat Gold: Bullion-Grade and Built to Last
22-karat gold, .9167 fine, is also bullion-grade, and its added alloy content makes it more scratch-resistant than pure 24-karat gold, which is why it is the standard behind the American Gold Eagle and the South African Krugerrand.
The U.S. Mint notes that “American Eagles use the durable 22-karat standard” and that the coins “contain their stated amount of pure gold, plus small amounts of alloy.” A 1-ounce American Gold Eagle is 91.67% gold, 3% silver, and 5.33% copper, and it still delivers a full troy ounce of pure gold, the alloy adds weight and hardness without shorting the buyer on gold content. The Krugerrand follows the identical formula. Its producer, Rand Refinery, describes it as “made from 22 carat gold, 9167 of pure gold and 833 parts copper,” again a full troy ounce of pure gold per coin.
The copper in both alloys is doing real work. Copper hardens gold considerably compared with the nearly pure metal in a 24-karat coin, which is why 22-karat coins tend to show less wear from stacking, handling, and circulation over decades of ownership. That durability is the entire case for choosing 22-karat over 24-karat as an investor: the metal content is slightly lower per coin by weight of gold relative to total coin weight, but the coin itself holds up better outside a sealed capsule or a bank vault.
18-Karat and 14-Karat Gold: Jewelry Alloys, Not Investment Bullion
18-karat gold, .750 fine, and 14-karat gold, .5833 fine, are jewelry alloys built for wearability, not investment-grade bullion, and neither is the purity level bullion dealers, refiners, or IRA custodians deal in.
A quarter to nearly half of an 18-karat or 14-karat piece by weight is alloy metal, added specifically to change color, harden the gold for everyday wear, and lower the cost of the finished piece. That is the right design goal for a ring or a chain meant to survive years on someone’s hand or neck. It is the wrong purity level for a buyer trying to own gold as a store of value, because a large share of what is bought is not gold at all, and jewelry pricing folds in design, craftsmanship, and brand premiums that have nothing to do with the metal’s spot value. Bullion dealers, refiners, and precious-metals exchanges price almost exclusively in 24-karat and 22-karat product for exactly this reason.
The IRA Fineness Floor: Which Karats Actually Qualify
A gold IRA imposes its own legal minimum fineness of .995 under IRC § 408(m)(3)(B), the same standard the CME/COMEX exchange requires for gold delivered against a futures contract, with one statutory exception carved out for specific named coins.
Neither 24-karat nor 22-karat gold automatically clears that IRA bar just by being investment-grade bullion outside a retirement account. The statute sets up two separate pathways. The first is the bullion pathway, and it requires gold to assay to at least .995 fine and sit in the physical possession of an IRS-approved trustee. 24-karat coins and bars easily clear that line, since .999 to .9999 fine is well above .995. 22-karat gold at .9167 fine does not clear it on fineness alone.
The second pathway is a named-coin exception under IRC § 408(m)(3)(A), which lists specific coins as eligible regardless of their exact purity. The American Gold Eagle is the exception that matters here. Even at .9167 fine, well below the .995 bullion floor, the Eagle qualifies for an IRA because it is named directly in the statute as a gold coin described under 31 U.S.C. § 5112(a). That is a legal carve-out for one specific coin, not a purity workaround an investor can apply to any 22-karat product.
The Krugerrand does not get the same treatment. It is also 22-karat, .9167 fine, and it is not named in the U.S. statute’s coin exception, so it fails both pathways at once, too low in fineness for the bullion route and not on the named-coin list for the exception route. It is treated as investment-grade bullion in the open market, but it cannot sit inside a U.S. self-directed IRA.
| Coin or Product | Karat / Fineness | Mint or Refiner | IRA Eligible | Pathway |
| American Gold Eagle | 22k / .9167 | U.S. Mint | Yes | Named-coin exception |
| American Gold Buffalo | 24k / .9999 | U.S. Mint | Yes | Bullion pathway (above .995) |
| Canadian Gold Maple Leaf | 24k / .9999 | Royal Canadian Mint | Yes | Bullion pathway |
| Austrian Gold Philharmonic | 24k / .9999 | Austrian Mint | Yes | Bullion pathway |
| Australian Gold Kangaroo | 24k / .9999 | Perth Mint | Yes | Bullion pathway |
| Gold bars, LBMA Good Delivery | 24k / .995 or higher | Accredited refiners | Yes | Bullion pathway |
| South African Krugerrand | 22k / .9167 | Rand Refinery / South African Mint | No | Fails .995 floor, not a named coin |
| 18-karat or 14-karat jewelry | .750 or .5833 | Various | No | Fails .995 floor, not a named coin |
Custody matters as much as fineness. Even fully eligible metal loses its tax-advantaged status if it does not sit with an approved trustee rather than at home, a distinction the U.S. Tax Court reinforced in McNulty v. Commissioner. The karat and fineness question decides whether a product can qualify at all. The custody question decides whether it stays qualified.
Frequently Asked Questions
Is 24-karat gold always better than 22-karat gold for investing?
Not necessarily. Both are investment-grade. 24-karat delivers slightly more pure gold content relative to total coin weight, while 22-karat holds up better to handling and long-term storage because its copper alloy hardens the metal. The choice often comes down to whether an investor values maximum purity or a coin built to withstand decades of stacking and handling.
Can I invest in 18-karat or 14-karat gold?
18-karat, .750 fine, and 14-karat, .5833 fine, are jewelry alloys, not bullion. They carry value as finished jewelry pieces, including craftsmanship and design, but bullion dealers, refiners, and IRA custodians do not treat them as investment-grade gold.
Is the Krugerrand IRA eligible?
No. At .9167 fine, the Krugerrand falls below the .995 minimum fineness required under IRC § 408(m)(3)(B), and it is not among the coins named in the statute’s exception, so it cannot be held inside a self-directed IRA even though it trades as investment-grade bullion outside one.
Why does the American Gold Eagle qualify for an IRA at only .9167 fine?
The Eagle qualifies through a separate statutory pathway, the named-coin exception under IRC § 408(m)(3)(A), which lists specific U.S. gold, silver, and platinum coins as eligible regardless of their exact fineness, rather than through the general .995 bullion floor that applies to everything else.
What fineness does a gold IRA require?
Gold held inside an IRA generally must assay to at least .995 fine under IRC § 408(m)(3)(B), the same minimum the CME/COMEX exchange sets for gold delivered against a regulated futures contract, with the named-coin exception as the sole carve-out.
This article is educational only and does not recommend, review, or promote any dealer, custodian, or investment product. Always weigh karat and fineness decisions against your own plan, and consult your own financial and tax professionals before acting on them.
About Sean Webster
Certified Public Accountant specializing in retirement planning, alternative investments, and tax-advantaged investment strategies. Reviews investment content for accuracy and regulatory compliance.