New York ? Before you bought a used car, you’d have it checked out by a mechanic. So too, when you buy valuable jewelry, you should get it appraised first.

Not doing so is a mistake that could eventually cost you, says David Hendry, president of JCRS Inland Marine Solutions, an insurance company that specializes in jewelry appraisals. While a good appraisal provides written assurance of the jewelry’s quality and helps your insurer set proper premiums, a bad appraisal could leave you with nothing if the jewelry must be replaced.

Appraisals should include the estimated replacement value of the jewelry, a description of all characteristics of the piece, a list of gem treatments, a photograph, classification of the gem as natural or synthetic and the manufacturer, metal and karatage of the mounting. You might print out a copy of the ACORD 78, an insurance-industry standard form for jewelry appraisals. You can get it from www.jcrs.com.