Today at the Old School we’re going on a field trip, to learn a little something interesting about sparkly stuff.
Back in the olden days (and by that the Damsel means WAY long ago), people used to weigh gems to determine their value, just like we do nowadays. But of course there was no such thing as a digital scale…
So, it just so happens that the carob seed grows remarkably consistent in size and weight. So this humble little seed was used for centuries as a standard for weighing precious stones.
Then perhaps a gemsmith came along who was rudely trying to speak with his mouth full of peanut butter, and when he said “carob” it sounded like “carat” or “karat.”
From then on, the weights of gems have been measured in karats. One karat has been standardized worldwide to equal 0.2 grams.
Measuring the pureness of gold in karats is different. It’s not a weight, but a percentage of purity. 24 karat gold is 100% pure gold, while 18k is 75% pure and 12k gold is 50% pure.
It’s sort of confusing to use “karat” in these two ways, and people who deal with gold are gradually shifting to a decimal based system. For example, 22k gold is marked as “916″ under this system, or 91.6% gold.
The Damsel just learned this TODAY. She doesn’t fool around with gold all that often. Still, it’s interesting to know.