Diamonds symbolize love and prosperity. Because diamonds are the hardest substance, they also sometimes symbolize endurance or perseverance. The rarity of diamonds, which makes them expensive and difficult to acquire, adds to their mystique and symbolic meaning.
Diamonds first emerged as a symbol of engagement in the 15th century when European royalty began using them as a way of publicly demonstrating a promise to marry. The 60th wedding anniversary is also known as the "diamond anniversary" because the longevity of couples who live long enough to be married for 60 years is represented by the diamond. It is also the birthstone that represents the month of April.