How does one go about selling good jewelry?

I inherited a gorgeous platinum, aquamarine and diamond necklace, earrings and ring set from a relative who passed away 15 years ago. I’ve kept them out of sentimental value, and have never worn them because I don’t go to places where they would be appropriate. They’ve been sitting in a safety deposit box at the bank for over 15 years.

I would like to sell them, but have no idea how to go about it, or how to find a jeweler who would best handle such a transaction. I assume I would need an appraisal and an insurance rider before I even showed them around. Where do I start? What do I avoid?