So it wouldn't actually appraise for a higher value. Ideally, what you Jeweler told you is the way it should work. Then the consumer pays premiums based on actual value and the jeweler bypasses liability associated with inflated appraisals. An appraisal should give a realistic value so you can walk in to any store and purchase the same item again. If the jeweler gives you a deep discount and the item is lost and say for example you have moved to another state, you may not be able to get that same deal again.
Prices vary greatly because of the amount the appraiser marks the item up.
I won't give away any secrets but you can ask the appraiser for a reasonable replacement cost and they will get the idea. It's amazing how many people are fooled by the inflated appraisals. This is what the so called deep discounts have done to all retail bussiness. To give a Big Discount, you have to have a Big Mark Up, and in general the public falls for it each day. Just watch TV and you'll see this 24 hours a day.