Talk:Carat (mass)

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US spelling[edit]

Resolved: Moot; discussion predates splitting into separate articles.

I removed "(spelt karat in the U.S., to distinguish it from the unit of mass above)" because (a) I've never seen that spelling, (b) the OED states that it is an obsolete late Middle English spelling, without any note that it's still used (or ever has been used) in the US.

It is the only usage for a unit of purity in the U.S. I have ever seen. Consult a reputable American English dictionary (such as Merriam-Webster). And in fact, the OED states that it is "obs. exc. U.S." which means obsolete except in the U.S. and even gives several examples of its use in U.S. mass-market periodicals. --Grouse 13:48, 23 Nov 2004 (UTC)

correct mass definition[edit]

defines a carat as: CARAT 1) A measure of the weight of precious stones. 1 carat = 0.2053 gm.

other places define it as 1 carat = 0.20000... grams exactly. Which is correct? —Preceding unsigned comment added by (talk) 06:20, 29 November 2007 (UTC)

The above reference defines it as a weight not as a mass -- (talk) 03:36, 8 July 2010 (UTC)

Link now at --Rumping (talk) 03:30, 27 February 2011 (UTC)

Connection to Troy Measure[edit]

It was originally connected to the Troy system, but how many grains were in one carat?

In the UK, the weight of the carat was determined by the Board of Trade. For much of the 19th century, an ounce troy of 480 grains troy had exactly 151\,\tfrac{27}{64} carats; thus, during this period one carat was exactly 3\,\tfrac{1647}{9691} grains troy (about 205.4094 mg). In 1888, the Board of Trade reduced the weight of the carat so that an ounce troy had exactly 151½ carats; thus, one carat then became exactly 3\,\tfrac{17}{101} grains troy (about 205.3035 mg).
Kindly note that the carat was also divided into exactly four diamond grains, and that the diamond grain was not identical to the grain troy.
Podagratus 20:56, 16 February 2007 (UTC)


Is it time that we can have this as an article, rather than a stub? Samfreed 08:28, 17 February 2007 (UTC)

Yes, it’s time — I’ve just destubbed it.
Podagratus 07:57, 21 February 2007 (UTC)
Perhaps, but it still reads like it was written by school children. Someone needs to start from the top and rewrite this from the sources as a cohesive piece instead of a collection of sometimes contradictory trivia. — SMcCandlish Talk⇒ ʕ(Õلō Contribs. 20:57, 6 January 2012 (UTC)