It's a great idea - essentially Netflix for jewelry. It's a great way to add some sparkle to your bridal ensemble without blowing your budget.
You can rent pieces as singles or in sets, and by the week or by the month. And, yes, if you absolutely fall in love with a piece, you can work out a way to buy it.
It's your inner beauty that shines the most on your wedding day, but it doesn't hurt to have a little shiny on the outside too!