Anyone ever sell gold/diamonds?

Anyone ever sell gold/diamonds?

I came across my old wedding set in a box. (Old as in from my previous and unlamented marriage.) It's not a huge thing- a slim gold band and a solitaire engagement ring with a 1/2 carat diamond. Has anyone here successfully turned such items into cash? Any recommendations of companies to try or to be wary of or tips on how to go about selling would be much appreciated. I know there are places that will send you a mailer to send your stuff to them but I'm hesitant to just mail off a diamond to a company with no references.
My dorm room/apartment

My dorm room/apartment

Peonies almost  in bloom

Peonies almost in bloom

New at growing

New at growing

Roses

Roses

Plant ID, please?

Plant ID, please?

My room!

My room!