If you refuse the return and Ebay refund the buyer from your funds, you will get a defect on your selling account. This lasts a year.
This may be tough advice but this is genuinely what I would do:
Refund the buyer without requiring return of the item. It's really not worth providing a return label for such a low cost item.
Write a polite response to the feedback.
If you refund, you could write:
'I am so sorry you were disappointed. I have sent a full refund without requiring you to return the pendant.'
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)