Rosa's heart was racing from the four cups of coffee she had just finished, but she thought she might be having a heart attack.
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.
Well, karats of gold are measured according to 24 karat being the gold standard. All karats are fractions according to how much pure gold they contain. 18 karat gold would then be 18/24, with the 24 referring to 24 karat gold. So there are 18/24 parts of gold, or 75% gold content in 18k gold. Similarly, 22k gold -- the next common percentage of gold for the 'k' mark -- is 22/24 parts pure gold.