Price is often confused with Value. The price is set by the merchant. The value, on the other hand, is determined by 2 processes - one being the Cost Approach and the other being the Market-Data Comparision approach. The actual price may be less than equal to, or greater than the value. This is why a professional appraisal is necessary.
The market-data comparision method involves researching appropriate markets for comparable jewelry.
The cost approach entails provides an estimate of how much it would cost to create an identical reproduction of the piece of jewelry in the current market. Typically, the cost approach is used when comparable pieces cannot be found on the market.
The professional appraiser considers both approaches, and employs the appropriate one.
In either case, a lot of factors determine the value of the jewelry, such as: