Your are correct! Very common scam. To order jewelery and send back different item.
Always take pics of item before you send when dealing with high cost items. If your new to Ebay they probably saw you feedback number and figured you were easy prey. Best action is to contact ebay and make aware of the problem so that they can monitor buyers actions and see if their is a trend.
Otherwise I would not worry worst thing they can do is give you a bad feedback unless they paid with paypal. Then they can file a dispute in which all of you will get to state your case and then a final decision is made. Could go either way.
Bottom line is your suspicions are more than likely correct and take no action other then to let them know you have contacted ebay and made them aware of the claim.
In the future, make sure your transactions say "no refunds". Yes, the worse that can happen is you get a bad review from the buyer. And you can reply to that, stating your case.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.