Why does the appraisal expire after 3 years?

Market values constantly change, whether it be for houses, gasoline, groceries, precious metals, or gemstones.  Most jewelry appraisals are performed for insurance purposes, and AIGR's gemologists want to make sure that you are adequately insured without paying excess premiums.  So whether the market goes up or down, it is good to have a current appraisal.  Some insurance companies require that an appraisal be updated regularly, and if you change your policy, they may require an appraisal that is less than one year old.