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What fineness means (.999, .9999, .900, .925)
Fineness is parts per thousand of pure metal. .999 is 99.9% pure. .900 is 90%. Jewelry karat is the same idea in twelfths.
Fineness is purity written as parts per thousand.
- .999 = 99.9% fine (common silver bars and many silver coins)
- .9999 = 99.99% (Maples, some bars)
- .925 = sterling
- .900 = US coin silver
- .9167 ≈ 22 karat (Eagles, Krugerrands, sovereigns)
On those 22k one-ounce coins the coin is heavier than an ounce so the fine gold still equals the stated ounce. Gold Eagle. Maple.
Karat is the same pie
24k is “pure” in jewelry talk. 18k is 750 fine. 14k is 583. 10k is 417. Karat. Hallmarks.
Why an extra nine is not automatically more money
A shop is buying metal they can resell. A no-name .9999 bar can bid worse than a known .999 bar. Recognition beats a purity contest. What .999 guarantees. Government vs generic.
The stamp is a claim. The test is the bid. Tests. Sterling vs plate.
Continue in the coin and money library. Related visitor guides: for shop visitors.