Even though we're not supposed to say it, I love diamonds. (They're just so sparkly!)
My other two favorites are amethyst (my birthstone) & emerald.
My brother's birthstone is emerald & I can remember when I was a little kid I was so jealous because I thought emeralds were sooo much prettier! But now I like them both a lot.
Last xmas my boyfriend got me a white gold ring with an amethyst that I adore & wear every day.