Talk:Carat (purity)

If 18 carat gold is 75% gold, what is the other 25%?

Other metals, chosen for colour and hardness. Silver, Copper, Zinc and Nickel are often used. --W(t) 20:40, 15 February 2006 (UTC)

The Ottawa Mint in Canada is able to produce 59K gold, which I believe is 99.99999% pure gold compared with 49K 99.9999% pure gold. IDK?

Spelling - "carat" versus "karat".

Any views on this? It is my understanding that the "carat" form is used for mass, and the "karat" form for proportion. In any case, the use in this article is inconsistent. 20:45, 18 September 2007 (UTC)

In the intro the article says: " In the United States and Canada, the spelling karat is now solely used for the measure of purity, while carat solely refers to the measure of mass weight" but this needs to be better phrased and the article spelling should be consistent with the title. --mervyn 12:30, 19 September 2007 (UTC)

Volume

I removed the section below -- probably original research and not relevant since measure by volume is not used. --mervyn 12:45, 23 September 2007 (UTC)

What was removed is downright pedantic - has no bearing or usefullness to anyone in the real world. Gold is alloyed by weight in industry, and the rest is of minor curiousity to the writer, perhaps. In other words, good job, IMO Jjdon (talk) 19:45, 14 January 2008 (UTC)

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However, this system of calculation gives only the weight of pure gold contained in an alloy. The term 18-carat gold means that the alloy's weight consists of 75% of gold and 25% of alloy(s). The quantity of gold by volume in a less than 24-carat gold alloy differs according to the alloy(s) used. For example, knowing that standard 18-carat yellow gold consists of 75% gold, 12.5% silver and the remaining 12.5% of copper (all by weight), the volume of pure gold in this alloy will be 60% since gold is much more dense than the alloys used: 19.32 g/cm³ for gold, 10.49 g/cm³ for silver and 8.96 g/cm³ for copper.

This formula gives the amount of gold in cm³ or in ml in an alloy:

$V_{\mathit {Au}}={\frac {M_{a}\times {\tfrac {kt}{24}}}{19.32}}$

where

$V_{\mathit {Au}}$ is the volume of gold in cm³ or in ml,

$M_{a}$ is the total mass of the alloy in grams, and

${\mathit {kt}}$ is the carat purity of the alloy.

To have the percentage of the volume of gold in an alloy, divide the volume of gold in cm³ or in ml by the total volume of the alloy in cm³ or in ml.

For 10-carat gold, the gold volume in the alloy represents about 26% of the total volume for standard yellow gold. One should be aware of this, since talking about purity according to weight could lead to some misunderstandings; for many people, purity means volume.

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      y is gold counted by karat and not by percent?

International

Can someone double-check the data for Russia/former USSR? The typical value cited in the article is 14 karat, and I'm pretty sure that it was and is higher. —Preceding unsigned comment added by 24.4.205.124 (talk) 23:38, 28 September 2007 (UTC)

initials for gold jewelry

14KP I was told this was plumb gold very pure. Iv'e never heard of this, does any one know?****

Carmen —Preceding unsigned comment added by 70.234.201.86 (talk) 01:39, 16 May 2008 (UTC)

14 carat discrepancy

I found another Web site that also described 14-carat gold as 58.5 percent pure; my calculator's telling me it's 58.33 percent. It's not a huge discrepancy, but is one number accepted by industry and one by mathematicians? --Thatnewguy (talk) 16:44, 20 August 2008 (UTC)