A birthstone is a gemstone associated with a month in the calendar, and often worn as jewelry by a person born in the associated month. Each month (January through December) has a birthstone, and some months have an "alternate" birthstone, such as November where the birthstone can be either Topaz or Citrine.
Historically birthstones were based on astrology, and each stone was fabled to have its own properties and characteristics, for instance, turquoise was thought to have healing properties and bring good fortune to the wearer. Some birthstones have also been used to denote status, such as Amethyst which was once worn to symbolize royalty.
Chart of birthstones:
- http://www.americangemsociety.org/birthstones.htm?gclid=CLu6o5CW-pACFRsTawodHiK31Q - American Gem Society List of Birthstones