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.
Pure gold is too soft to be used in everyday jewelry, so it is alloyed with other metals to make it stronger and more durable. Pure gold is 24 karat, and 14 karat gold refers to an alloy of gold that contains at least 58.3% pure gold by weight. The balance is made up of other metals to give it strength. Gold is often alloyed with copper, silver, and zinc. Copper is ductile and hard, but tends to tint the alloy pink and is prone to oxidizing.