I have a 100% feedback rating on both Etsy and eBay and have never received any negative response and gotten a ton of praise!
My return policy is normally 'no refunds' for a couple of reasons.
1. It's jewelry (so for hygienic reasons, it's not a good idea), and
2. By the time the customer pays for the postage both ways, and then I factor in the costs charged by paypal fees, it's usually not worth it for either the buyer or myself once all that is factored in. I also price my jewelry very fairly keeping all of this in mind.