Sapphire comes in every color but red, with the most popular color being blue. Since early times, the gem has been linked to royalty and romance. Famously, Princess Charles proposed to the late Princess Diana with a blue sapphire ring, which the Duchess Kate Middleton now wears as her engagement ring. The gem stands for nobility, truth, sincerity, and faithfulness. Sapphire is the birthstone for September and the gem for the 5th and 45th anniversaries.