http://www.someecards.com/love/dating-relationships/woman-womans-response-to-wedding-rig/I've had someone tell me how small my diamond was too. And not in a polite "oh it's small in a cute way" either. It was meant to put me down. I know friends who got rude comments about their engagement rings as well. I love this article though. More people should read this.
and fwiw - I love her ring!