There is NO SELLER PROTECTION - its all a Sham - they say there is all these protections but EBAY HATES SELLERS, LOVES BUYERS - they don't give a Hoot about us Sellers 

It happened to us last year Buyer Lied and got away with Our Driving Lights and Our Funds - I proved everything to Ebay over a 4 to 5 month period but we still lost Ebay sided with the Buyer 

i would be telling your Bank to Reverse Ebays Deduction of the Funds - Tell your Bank its a UNAUTHORISED TRANSACTION , this what we will be doing if we ever have this problem again

I had this happen last year. It was sent tracked and marked as delivered, closed in the buyer's favour and ebay copped the bill out of their own pocket.

Now I know never to sell to that person again.

I had much the same thing happen to me. The buyer said the payment was unrecognised several months later, I tried to tell ebay that it was a scam, I had received positive feedback from buyer etc. They still ruled in favour of buyer. The email I received from ebay told me this then said case closed .I had no way to contact them again. Madness!!

Do you know for sure that the address you posted the necklace to is the address of the "buyer" who disputed the transaction?

I would contact the "buyer" and ask for them to provide a stat dec that they do not have the necklace and tell them you want the stat dec because you are involving the police in this.
I would send a letter to the same address you sent the necklace and explain that as the "buyer" has been refunded you need the necklace returned asap or you will have to involve the police.

I would state a date by which time you need a reply.
You might have some success but if there are no replies by a date set by you then go to the police oline fraud squad.

If you are uncomfortable confronting the "buyer" and the person who received the necklace then just go to the police and hope they can sort it out.

are you saying that the buyer did not authorise the transaction, so it is a chargeback?

@dudu-sydney, 

If you sent this item with tracking, and that tracking shows that the item was delivered, I’m surprised that seller protection isn’t in place for you.

As per eBay’s Help page for Seller Protection:

❝When a buyer opens a payment dispute because they didn't receive the item or they don't recognise the transaction

When a buyer opens a payment dispute because they didn't receive the item or they don't recognise the transaction, sellers will be asked to provide:

• Evidence of successful delivery to the address provided by the buyer at checkout, or
• Proof that the buyer collected the item

If eBay determines that the item was successfully delivered or collected:

• We will not seek reimbursement from the seller for the disputed amount, even if the payment institution decides that the buyer is owed a refund; and
• We will waive or refund the seller's dispute fee

Evidence of successful delivery

Tracking information from a carrier that shows all of the following:

• A delivery status of "delivered" (or equivalent in the country to which the item was delivered);
• The date of delivery;
• The recipient's address that matches the one found on the Order details page, including the city/suburb or postcode (or international equivalent); and
• Proof of signature confirmation uploaded as an image while challenging the payment dispute, for orders with a total cost (including postage and any applicable taxes) of $750 or more. Learn more about our signature confirmation requirements❞

The only thing I can think might be a valid reason for your not having seller protection - if the item was sent tracked to the buyer’s address and there is a status of “delivered” - is if the item was over that $750 threshold and there was no signature.

Otherwise, get on to eBay Lice Chst and ask to be contacted to a supervisor, quoting the policy information as I’ve quoted here, and pointing out that you provided proof of delivery as required and that you should not be liable for refunding the buyer.

Please come back and tell us if this successful. I know that I and the various other helpful responders on these boards value that feedback so that we can be sure we’re not giving incorrect information.

Unfortunately I don't think you can do anything retrospectively. Unfortunately these days, the really good and knowledgeable members no longer post here which is why you have likely not received any replies. 

If I was selling anything of high value and jewellery or something like that, I would probably have it authenticated by a reputable agent prior to selling. Even then, that might not help much but it is something you could put in the item description, it might make scammers less likely to bother. All you can sometimes do on eBay is make things much harder for scammers. Does the buyer's feedback indicate anything that might suggest they regularly get 'freebies' or have issues? 

You could always, inform them that you wish to have your item back otherwise you will be filing a Police report and/or file a claim with ACCC's Scamwatch ( I think that is the right body). If you had the original receipt you could always try to contact eBay with that to prove its authenticity. None of this will likely get your money back (it could if you kick up a fuss with eBay, not sure if they have a Facebook account these days but there were times in the past that the bad publicity made them take action on certain cases), but it might at least let the 'buyer' know that they are now on 'watch' by the authorities. Sorry I don't have better advice for you. 

I too am extremely frustrated at the lack of support for sellers when buyers claim 'item not as described' - as sellers we are not offered the right of response and just told to cough up the cash - and lose out on postage that ebay has already chewed into with fees.  Sorry i don't have any advice for you - but defineilty understanding your frustration.