"Karats" measured by weight or volume?

Don A. Gilmore · 2004-10-29T17:50:27+00:00

You guys are not following me. The purity has to be measured somehow:either weight or volume.Here's an example. If I take one cubic inch of gold and one cubic inch ofaluminum and mix them together I should get two cubic inches of alloy thathas a purity of 12 karats (50% of 24), but ONLY if I'm measuring karats byvolume.One cubic inch of gold weighs .6969 lbs. One cubic inch of aluminum weighs.0975 lbs. So the total weight of the 2.0 cu. in. of alloy is .6969 + .0975= .7944 lbs. So the percentage of gold by WEIGHT would be.6969 / .7944 = 87.7%Gold accounts for 87.7% of the total weight of the alloy. This results in akarat of.877 x 24 = 21.05k (by weight)which is nowhere close to the "volumetric" karat of 12k.Now, let's say I mix one cubic inch of gold with one cubic inch of copper.Volumetrically I still have half gold, or 12k. But a cubic inch of copperweighs .3210 lbs. So the total weight of the alloy is .6969 + .3210 = 1.018lbs. and the percentage of gold by WEIGHT is.6969 / 1.018 = 68.5% = 16.4kSo by changing the alloying metal I have considerably changed the karat, ifindeed we are to use weight to determine karat, even though the size of theresulting alloy (2.0 cu. in.) is the same.Now do you get what I mean?DonKansas City

Oct 29, 2004 20 Replies

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John Ferman 21 years ago

Okay. How do you measure mass all by itself? Device and units expressed.

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"Karats" measured by weight or volume?

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