carat

Sometimes late at night when I'm tired but not really tired enough to sleep I find myself watching Jewelry Television. For me, home shopping channels are oddly mesmerizing, even though I've never had the slightest inclination to buy anything, but lately it's really the jewelry that I find most fascinating.

This is hard to explain, as I have never had much interest in jewelry stores or even jewel exhibits at museums. I don't wear jewelry and have no desire to do so. But for some reason, the enthusiastic presenters at JTV always reel me in. Woo hoo! one says--look at the flash off of that opal!

I have no idea if any of the gemstones they are selling are actually valuable, but it sure is fun listening to them make it sound as if they were. (There's a good novel, by the way, about the art and con artistry behind the jewel business--How to Sell, by Clancy Martin, which I reviewed awhile ago here . 

But despite listening to the JTV argot, I realized recently, that I really have  no idea what a carat is. Although I think we tend to associate the word carat with diamonds, they come up in all kinds of gemstones. I assume that "carat" has something to do with weight, for what else could it be, but it's odd how little carats seem to have to do with the size of the stone.

Well, let's get to it.

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Sheesh. Nothing is ever just easy, is it? Let me start by admitting that I wasn't really entirely sure how to spell "carat" going in. Maybe that's because there are actually two spellings of it. Carat, yes, but also karat. As far as I can tell from this interesting post about the distinction, both variants go back to the same source, but have taken on different meanings. In American English, the convention has arisen to say that carats have to do with mass and weight, while karats have to with purity. In British English the same spelling is used for both senses.

The word goes back to the Middle French carat, which had to do with measuring the fineness of gold, derived from the Italian careto , which was taken from the Arabic quirat, meaning pod or husk, or four grains of weight, and then back to the Greek keration, carob seed. In early, predigital times, the carob seed was used as a standard of weight because of its uniformity, just as a grain was used as a standard of a far smaller weight.

the name carob comes from the Greek word kera, or horn, which describes the shape of the pod, not the seed.

To get really bogged down in obscurity, the Greek weight was equal to one Roman siliqua, which in turn was 1/24th of a golden solidus of Constantine. This is important because keration then took on a sense of  being a proportion of  1/24th, which then became a measure of gold purity. This is why when something is advertised as 18 karet gold, it should have 18 parts of gold to 6 parts of alloy. And why 24 karat gold is usually followed by an exclamation point.

But when it comes to gemstones, a carat is a unit of mass. A carat is equal to 200 milligrams. But it still derives its name from the lowly carob seed. The confusion is not a late add on, but arose from the unit of measurement itself.

Gold prices being what they are right now, there are more carats than karats being featured on JTV these days. By the time the bubble bursts on gold, I'll probably have a pretty good handle on the difference.