I purchased a tanzanite ring and wore it approximately 20 hours. I was very careful with it, didn't hit it on anything. A stone fell out, which means it was not secured in the first place. I spoke with someone online in another country, of course, and then spoke with someone on the phone. They will not deviate from their 15 day return policy, no matter the reason.
Their quality is inferior, the shipping is too high, and their customer service is beyond despicable. My advice is to never buy from bidz.com.