The double certificate of sheep fat jade means that sheep fat jade has two certificates, namely the appraisal certificate and the collection certificate. The appraisal certificate is a certificate issued by the national jewelry appraisal department after instrument testing, which proves that the jade is pure natural Hetian jade. Collection certificate is a certificate used by sculptors to reflect the value of their works. The double certificate means that there is a certificate from an authoritative organization to prove that this jade is pure natural Hetian jade, and there is a special Xinjiang organization to prove that this jade can reach the level of sheep fat jade. This is the most responsible way for Baoyou.