Rule Number 1:
If it looks delicate it is delicate
This seems like a simple rule, but it is often forgotten. Try to remember that the first people to wear fine jewelry were royalty and that they were rarely found washing the dishes or moving the piano. Mountain biking, gardening, rock climbing and kayaking are all dangerous for jewelry. If you are a brute, wear a ring that has some substance. And few necklaces appreciate the tossing and turning that happens while you sleep.