As a gemmologist/designer, I find conversation at dinner parties will often turn to jewellery.
I'm always interested in what others are wearing: where it's been made, the history of it, the significance to the owner - and I always have a close look at the condition of it. Like many other things, jewellery requires regular check-ups and maintenance. I recently looked at a friend's original engagement ring and was horrified to see several of the claws holding a very substantial diamond were missing completely. She had no idea, as she hadn't looked closely at her ring for a while, so I suggested that she take it off right then and there. That was a very close call and could have caused her a lot of heartache, not to mention the actual cost of replacing the stone.
As well as regular check-ups of your diamonds and other gems, don't forget to clean them at least weekly, if you wear them every day.