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21K Gold Purity

What 21K gold means: 87.50% gold, stamped 875, with the pure gold weight per tola and per troy ounce.

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In short 21K gold is 21 parts gold in 24, which works out to 875.00 parts per thousand and 87.50% gold by weight; the remaining 12.50% is alloy, usually copper, silver, zinc or nickel, and it is what sets the colour and the hardness. It is stamped 875. Here the arithmetic lands exactly on the mark, so 875 needs no rounding at all. In practical weights, one tola of 21K — 11.6638 grams gross — contains 10.206 grams of pure gold, and one troy ounce of it contains 27.216 grams; gold is priced per troy ounce of 31.1035 grams, never per the 28.35 gram ounce on a kitchen scale. This is the standard in UAE, Saudi Arabia, Kuwait, Egypt, where it is used for the Gulf jewellery standard. One thing to keep straight: karat is a ratio out of 24 and says nothing whatever about weight, while the carat that gemstones are sold in is a mass unit of exactly 0.2 grams. A two carat stone weighs 0.4 grams; a 21 karat piece can weigh anything at all.

How to use the 21K Gold Purity

  1. Read the fineness and percentage for 21K.
  2. Check the pure gold weight per tola and per troy ounce.
  3. Switch the selector to compare with another karat.

About the 21K Gold Purity

What 21K gold means in fineness, percentage and pure gold weight, and where it is the standard.

What people use it for

  • Reading a 875 hallmark and knowing what it guarantees.
  • Working out the gold content of a 21K piece.
  • Comparing 21K against the other standards before buying.

Details

Fineness875.00 parts per thousand
Gold content87.50% by weight
Hallmark875
Pure gold per tola10.206 g of 11.664 g
Standard inUAE, Saudi Arabia, Kuwait, Egypt
PrivacyEverything runs in your browser. Nothing you enter is sent anywhere
The fineness on this page is derived from the karat rather than stored, so it cannot disagree with the arithmetic. The mark is the published external figure.

Where this tool stops

Karat, fineness and percentage are definitional and never change. Everything involving money depends on the rate, the charges and the deduction you enter — none of which are stored on this site, because they move constantly. Hallmarking law and the legal minimum karat differ by country; check your national assay office before relying on a stamp.

Frequently asked questions

What percentage of gold is 21K?
87.50% by weight. That is 21 parts gold in 24, or 875.00 parts per thousand, which is why it carries the 875 mark.
Why is 21K stamped 875?
Here the arithmetic lands exactly on the mark, so 875 needs no rounding at all.
How much pure gold is in a tola of 21K?
10.206 grams, out of 11.6638 grams gross. A tola is 180 troy grains, which is exactly three eighths of a troy ounce.
Where is 21K the standard?
UAE, Saudi Arabia, Kuwait, Egypt. National standards are conventions rather than properties of the metal, which is why a piece bought in one country often does not match one bought in another.
Is karat the same as carat?
No. Karat is this purity ratio out of 24. Carat is a mass unit for gemstones, exactly 0.2 grams. American English often spells both the same way, which is where the confusion comes from.
Are there any usage caps on the 21K Gold Purity?
There is no cost and no cap. The 21K Gold Purity is not a demo of a paid product, so nothing is held back or watermarked.
Is my data uploaded anywhere?
No. The 21K Gold Purity runs entirely in your browser using JavaScript. Nothing is transmitted, logged or stored, which you can verify yourself in the Network tab of your browser's developer tools.
When would I actually need the 21K Gold Purity?
Typical uses: reading a 875 hallmark and knowing what it guarantees. Working out the gold content of a 21K piece. Comparing 21K against the other standards before buying. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
What are the limits of the 21K Gold Purity?
Karat, fineness and percentage are definitional and never change. Everything involving money depends on the rate, the charges and the deduction you enter — none of which are stored on this site, because they move constantly. Hallmarking law and the legal minimum karat differ by country; check your national assay office before relying on a stamp. Knowing where a tool stops being trustworthy matters more than the cases where it works.
What are the reference figures here?
Fineness is 875.00 parts per thousand. Gold content is 87.50% by weight. Hallmark is 875. These are printed on the page itself, so you do not have to take them on trust.
How precise is the result?
The calculation runs in double precision and the result is shown to ten significant figures, so converting a value and converting it back returns the original. What is displayed is rounded for readability; what is copied is not.

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