The idea of birthstones is one of the oldest jewelry traditions. Each month of the year is associated with a gem that is thought to be lucky and protective for a person born during that month. There also many other charts based on zodiac signs, days of the week, guardian angels, and other topics. For every chart topic you are sure to find several variations. The origin of birthstones can not be precisely identified, however, many gemologists agree this tradition stemmed from the twelve stone breastplate of the Jewish High Priest described in Exodus 39:8-14:
"8 They fashioned the breastpiece—the work of a skilled craftsman. They made it like the ephod: of gold, and of blue, purple and scarlet yarn, and of finely twisted linen. 9 It was square—a span long and a span wide—and folded double. 10 Then they mounted four rows of precious stones on it. In the first row there was a ruby, a topaz and a beryl; 11 in the second row a turquoise, a sapphire and an emerald; 12 in the third row a jacinth, an agate and an amethyst; 13 in the fourth row a chrysolite, an onyx and a jasper. They were mounted in gold filigree settings. 14 There were twelve stones, one for each of the names of the sons of Israel, each engraved like a seal with the name of one of the twelve tribes."