Diamonds are not a girl's best friend, so it seems

My fianc? bought a diamond ring in February from Intl Diamond Merchants via Bid or buy. We got engaged in May and last week one of the stones fell out. I notified Intl Diamond Merchants about what happened and then Candice informed me that they will replace the stone, but that I have to pay for the replacement and the courier fees. Because of the nature of the package it is expensive to courier the ring to Intl Diamond Merchants and I need to insure the package. When I told Candice about the costs involved, she suggested that I send the package via speed service and that it should reach them safely. This is not a viable option, because what if the ring is ****** or gets lost. I've asked Bid or buy for help and they say that Intl Diamond Merchant should refund or replace the ring and it should be sent to me at their own costs. When I informed Candice of this, she said the ring has been with me for longer than 5 months and they that they won't cover the costs, because it is a delicate ring with a lot of small diamonds and if diamonds become loose it is attributed to the usage of the ring. Well, by usage it must mean me wearing the ring. Well, I took care of it. What else must I do?