Hello Reed,
I think the best thing to start with would be organizing your products into categories that both bots and humans can semantically understand that will eventually lead to the actual urls you will use. What I mean is it would be better to have some form of:
example.com/bracelets/dangle-topaz-gemstone
example.com/topaz-gemstone-dangle-bracelet
example.com/dangle-bracelets/topaz-gemstone
It would be best to not go past the 3rd level if you can help it but if you have over 4,000 products it might be hard. When I did this for a company I found that the more time I spent on the organizational structure of the products, the better and more organized the URLs ended up.
Good luck!