Maybe message them back very politely saying your suprised to hear from them as the bracelet was sold as 9ct gold,and you have confirmation of this,so they must of mistaken you for a different seller.
The buyer is out of time to make any claim via ebay,and sounds like they maybe trying it on.
Be aware the buyer could try to recover the money by other means,but wait and see.
________________________________________________________________
"The secret of getting ahead is making a start"