I'm certain that the on site jeweller can give you a referral to a certified appraiser.
Give them a call and ask to speak with the jeweler. He is there nearly ever day. I'm not sure if he does bona fide appraisals but he is knowledgeable.
One day a month is appraisal day and you need to call and make an appointment. I went one day and was told that and it was the day I was there but had to make a appointment for the next month and the spots were filling up quickly.
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