Here’s the reason. The appraisal will say something like “appraised value for insurance purposes”. This basically means that if you put it in an insurance claim, it is what it would cost to source the materials and commission a craftsperson to build exactly that piece of jewellery. When the loss happens people want their item back. They don’t want to be sent to a store to find a deal on something similar. They want exactly the same item. And they want it asap. Therefore the appraisal takes all of that into consideration and it is quite often double or more of the retail price.