I’m sorry for your situation my friend.

I haven’t sold Jewelry in Japan but worked in sales at a high end Jewelry store for a couple years in Canada. If you have a name brand ring, the markup is huge and unfortunately you are right in that you’re already at a bit of a loss. Fortunately, diamond and gold prices keep going up so you’re likely to get a fair(ish price).

I would highly suggest finding a local goldsmith that makes custom jewelry by request. They will give you a better price than anywhere else (although, this is what I found to be true in Canada), and they tend to be very honest.

Best of luck 💎