The single most important caveat regarding appraisals is the fictitious inflated value appraisal. A simple rule to follow is that if it is too good to be true, it probably is. Misrepresentation of value is a major problem in the jewelry industry.
Another thing to be aware of is the opposite scenario of the “lowball” appraisal. Is the person who is doing the appraisal trying to sell you their item of jewelry by telling you that you overpaid for a piece of jewelry purchased somewhere else? While it is certainly possible that the professional opinion will lead to an unfortunate conclusion regarding the value, be sure that the opinion is not intended to get you a refund so that you can buy from the jeweler doing the appraisal. Often, a buyer will have remorse after a purchase and should they be looking for a refund, most likely they will need an independent appraiser that does not sell jewelry to offer an unbiased opinion of value.