22. What does carat mean?
Carat can have two meanings. It is a unit used to express the mass of a noblestem and it can be a unit used to indicate the content of gold or silver in jewelry, bars and coins. In the case of precious metals, the scale goes up to 24 carats. The gold content is expressed as a part of 24 parts. If it is pure 99.99% gold, then 24 out of 24 parts are gold and you speak of 24 carats. At 18 carats, 18 of the 24 parts are gold, or 75 percent. Gold bars are almost always 24 carats and with gold coins the gold content often varies from 21.6 carats to a maximum of 24 carats. Jewelry is usually 18 or 14 carats.
Many jewels are 18 or 14 carat gold. Gold bars are 24 carat gold
Source: Wikipedia
