I read a great editorial in a 1950's etiquette book years ago. The basic premise was that you should not feel you "have" to have a diamond as your engagement ring just because of social convention. If you're not feelin' it, get a pearl, opal or sapphire engagement ring, or maybe not a ring at all. Be true to yourself, not what the diamond/bridal industry tells you.
However, if you love diamonds, go for it.
