You probably know your birthstone, but do you know how that particular gem came to be associated with your birthday? It's a long story, one that dates all the way back to the book of Exodus. The prophet Moses had a brother Aaron, who in his capacities as the first high priest of the Israelites wore a ceremonial breastplate adorned with four rows of three precious stones to represent the 12 tribes of Israel. Interestingly, due to translating challenges, the exact stones that were included are somewhat of a mystery.
It wasn't until the first century A.D. that the Romano-Jewish scholar Titus Flavius Josephus connected the 12 stones to the 12 signs of the Zodiac. With that connection to the month of a person's birth, the jump from Zodiac stone to birth stone was a simple one. In 15th-century Poland, wealthy people would collect a full set of birthstones and wear each on its particular month in order to reap its mystical powers. In 1870, Tiffany & Co. published a pamphlet that included a poem that laid out the birthstone for each month, and finally in 1912 the National Association of Jewelers officially adopted a birthstone list. That list has been periodically updated with stone additions and changes ever since.