CARATKARATSoumya VhasureHayley Mellin

PROCEDURE How measuring units came to be. What tools were used? Who the major contributors were to the

development of the devices and units used.

What major blunders occurred because of faulty measurement?

CARAT Mass of diamonds, pearls, and other gemstones The word carat is derived from the Greek kerátion (κεράτιoν), “fruit of the

carob”, via Arabic qīrāṭ (قيراط) and Italian carato. Carob seeds were used as weights on precision scales because of their reputation for having a uniform weight. (However, a 2006 study[1] by Lindsay Turnbull and others found this not to be the case – carob seeds have as much variation in their weights as other seeds.[2]) This was not the only reason. It is said that, in order to keep regional buyers and sellers of gold honest, potential customers could retrieve their own carob seeds on their way to the market, to check the tolerances of the seeds used by the merchant. If this precaution was not taken, the potential customers would be at the mercy of "2 sets of carob seeds". One set of "heavier" carob seeds would be used when buying from a customer (making the seller's gold appear to be less). Another, lighter set of carob seeds would be used when the merchant wanted to sell to a customer.

In the distant past, different countries each had their own carat, roughly equivalent to a carob seed. In the mid-16th century, the Karat was adopted as a measure of gold purity, roughly equivalent to the Roman siliqua ( of a golden solidus of Constantine I). As a measure of diamond weight, from 1575, the Greek measure was the equivalent of the Roman siliqua, which was of a golden solidus of Constantine, but was likely never used to measure the weight for gold.[3]

http://en.wikipedia.org/wiki/Carat_(purity)

KARAT Purity of metals, especially gold, but also silver and platinum (

http://loupe-online.com/diamonds/diamond-carat.html) 24 karat = 100% pure 18 karat = 75% pure A carat is a unit of weight for diamonds and other gemstones. One carat

equals 200 milligrams (0.200 grams). There are 453 grams in a pound (1,000 grams to a kilogram). Therefore, if your fiancee weighs 170 pounds, you have a 385,050-carat fiancee!

A karat, when used with gold, is a unit of purity-- 24-karat gold is pure gold, but usually you mix gold with a metal like copper or silver to make jewelry (because pure gold is too soft). Each karat indicates 1/24th of the whole. So if a piece of jewelry is made of metal that is 18 parts gold and 6 parts copper, that is 18-karat gold.

Where did such a funny unit of purity come from? It turns out that a German gold coin called a mark was common about a thousand years ago. It weighed 24 carats (4.8 grams). The purity of the gold in the coin was expressed in the number of carats of gold present in this 24-carat coin.

http://science.howstuffworks.com/dictionary/geology-terms/question64.htm