A birthstone is a gift of a precious material (jewelry, mainly gemstones; themselves traditionally associated with various qualities) that symbolizes the month of birth (in the Gregorian Calendar) of the birthday boy or girl. It is sometimes also called birthday stone (cfr. infra; but that word is, confusingly, sometimes used as a synonym for an anniversary gift, which is related to the recipient's age, i.e. year of birth).
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 the most widely used list in the United States and many other places, including Australia (a jeweler's 'modern' list states they are selected for bright colors) and Thailand: