I've had great experience with the folks at Turgeon-Raine. They provided me with a professional appraisal of some jewlery that I inherited, which they also resized, cleaned, and repaired. They keep a copy of the appraisal on hand and will provide it to your insurance company directly (as well as providing you with a copy).
They provided a professional atmosphere with down-to-earth (not snobby) service in a very upscale environment. They finished my work early and stayed in touch throughout the process.