Boy I sure wish that people wouldn't buy into movie and internet propoganda so much!
First off, ignore what that butt-clown said.
Second, I agree about other posters have said -- the engagement ring is really the only ring that's "required" to be bought secretly. The wedding bands are usually purchased as a couple. It's hard to tell what guys like so let him spec out a couple of jewelery stores before making the final decision.
And unlike Master Genius said, wedding bands with diamonds are not purchased as a financial investment, but as a symbol for the emotional, mental, and physical investment that is being made. And if he did any research that mattered, he would realize that the markup on jewelry is already so high that the resell value is less than half of the initial purchase price.