Cos Altobelli, ECGA, is a third generation jeweler and president of Altobelli Jewelers in Burbank, California. In 1969, Cos earned a graduate gemologist diploma from the Gemological Institute of America as well as Certified Gemologist® title from the American Gem Society. He has been the Appraisals Committee Chair for over 25 years.
Cos organized the first formal appraisal education program in the United States, the Certified Gemologist® Appraiser for the American Gem Society. He has appeared on "Prime Time Live" assisting in exposés on diamonds, synthetic stones, and pearls. His appraisal expertise has been required at museums, legal and financial firms, and government agencies. He has written three appraisal books and donated hundreds of hours to the service of the AGS. The Cos Altobelli Library was named after Cos to honor his contributions to the Society.