The belief that certain stones had special virtues associated with months of the year and zodiac signs, can be traced to the first century AD.  Josephus in his writings, proclaimed a connection between the twelve stones in the High Priest's breastplate, the twelve months of the year and the twelve signs of the zodiac.  It was not until the 18th century in Poland, that there is any documentation of people actually wearing birth stones or zodiac stones.  People wore or carried gem stones at first, for their therapeutic and medicinal properties.  These properties were then associated with characteristics of the zodiac, making them talismans for those born in the same month. Birth stones, as we know them today, is a list of stones that was first assembled in 1912 by the American National Association of Jewelers. This list has historical merit, but substitutions have been made, based on relative availability.