Birthstone
A birthstone is a gemstone or other semi-precious stone which is associated with a month of the Gregorian Calendar. There is no particular connection between the stones and the months, but they are often used as a way to "personalize" jewelry, taking the stone for the month in which a person was born.
There have been many different sets of birthstones used throughout history and in different cultures, but in 1912 the American National Association of Jewelers, Jewelers of America, officially adopted the following list; it is currently accepted as the standard in the United States and many other places.