The tradition of birthstones stretches back centuries. They were thought to bring good luck and protection to the wearer. Many gemstones were also and still are considered to have healing properties. So when did the tradition arise? Some gem scholars consider the biblical Breastplate of Aaron (Exodus 28: 15-30) as the origin of birthstones. The twelve gemstones represented the twelve tribes of Israel. From there it was a short hop to the twelve months of the calendar and the twelve zodiac signs.

The number 12 also appears to be of symbolic significance to other ancient cultures so do check out these alternative birthstones found in Ayurvedic (Indian) and even Roman charts or lists (see reference below).

One beader made a necklace with the birthstones of each member of her family. As you can see from all the different birthstone charts available, you can choose another gemstone if you don't happen to like the first or if I don't have something in stock! Take topaz (November) for example: the yellow-light brown versions were prized long ago but there are also blue varieties which might be more suitable to some. I have citrine rather than topaz which is a substitute according to the modern birthstone chart. This chart is nearly 100 years old! It was first established in 1912 by the American National Association of Jewelers.

References

1. Gena Schwarm on the Burke Museum of Natural History and Culture, University of Washington, USA's website has written an excellent information guide on the science and legends behind birthstones:
http://www.washington.edu/burkemuseum/collections/geology/birthstones/

2.This fine jewelry store's website has a full list of all the birthstones including ones from older or other cultural lists as well as the anniversary list :
http://www.michaelsjewelrycenter.com/index.html

3. American Gem Society:
http://www.americangemsociety.org/