Is there a chance that my fiancee broke up because she saw that I gave her a fake diamond?

I bought a diamond engagement ring on eBay USA. The guy told me that it was a real diamond, I believed him. I gave it to my fiancee who accepted to marry me. 3 weeks later, she broke up. 3 months later, I resold the ring on eBay France, I lost $80 in the process and the buyer gave me negative feedback and told me that he brought it to a jeweller who said that it was oxyde of zirconium and not a diamond!
My fiancee told me several reasons (but not the ring) to break up but it was surprising because she changed her mind while I was in Miami and she was in Albuquerque. She told me 2 days before breaking up that she is not attracted by diamonds and would prefer a ring made by a famous designer.
Is there a chance that the real reason of the break up was that she went to a jeweller? Can a woman hide the real reason of why she break up?
To see the pictures of the ring, click at http://taxtipcalculator.com/ebay-craigslist/photos-ebay.htm

Well since she didnt bring up the case then that was not the reason, but still anyway, u can know by asking her.

_K_

Diamond Designer Engagement
Diamond Designer Engagement
Diamond Designer Engagement