BlueNile, JamesAllen, Amazon, Abazias and many others have 'affiliate' marketing programs where their goods are promoted on other sites and a commission gets paid if someone shows up through one of those links and buys something.
Slevesque, I'm curious. Do you count this sort of thing as good or bad? That is to say, would you prefer to buy from a dealer who is paying someone a commission or one that isn't? Is the goal here to get a commission out of your friend?
I've referred two friends to Whiteflash and got the referral gift since my husband got my engagement ring from Whiteflash. If you didn't buy an item from them, I don't think you'd get anything for referring a friend to them.