May want to look for a place that deals with estate jewelry.
If you are using a lawyer they can probable point you somewhere, but do not let them have it done.
I was charged more by the lawyer to get the diamond appraised than they said it was worth.
It was a very nice diamond from the 60s that I had the receipt for - its cost $750 in the early 60s. That is about 7500 today. They said it was worth 1200 and it cost me 1500 to have it appraised.
Yeah that lawyer was a bad choice, he worked at the court house and my parents chose him. Long story.
Be careful who you go to as there are a lot of scammers, sometimes they will take days to appraise your jewelry and what you get back may not be what you gave them.
As others said they will basically pay you as little as possible, not even going to get into the whole diamond scam.
No different than used car dealers, collectable dealers etc...
I had a very nice $300 dollar gold Claddagh ring, it was heavy and solid. Made in Ireland.
They offered my $15 for it, it may have been six moths old.
This was back in the late 80s. I doubt much has changed.
In the end I found it was not worth it to even bother when I was dealing with several estates and sold the stuff at a bargain to family members.