dazzabelle if the item was returned then you were only out of pocket by the postage. I would have offered the buyer a refund without them even having to open a dispute if I did not have proof of authenticity.  As I wouldn't want an unhappy customer I would probably have offered a refund on return even if I did have proof.

If it was advertised as a ruby then anyone could reasonably expect that it was not a created one they were purchasing and as you had never had it authenticated yourself you were almost bound to lose, the onus of proof is on you and if you had have had proof it was a natural ruby and genuine, hallmarked gold then once you provided that proof Paypal would very likely have found in your favour.