About GCAL

Gem Certification and Assurance Lab (GCAL) is a diamond research and identification laboratory specializing in guaranteed diamond grading:

  • Employs some of the top experts in the diamond grading industry.
  • Equipped with state-of-the-art technologies and instrumentation, including the DTC DiamondSure, DTC DiamondView and FTIR Infrared Spectrophotometer. Take our virtual tour.
  • Located in New York’s diamond building

    580 Fifth Avenue LL
    New York, NY 10036
    Telephone: 212-869-8985

GCAL is the only diamond grading company with a "Zero Tolerance" Consumer Grading Guarantee that provides cash-back for any error in grading or identification of the certified diamond. See Guarantee

GCAL Experts

Donald A. Palmieri Donald A. Palmieri
President, Gem Certification and Assurance Lab (GCAL), Master Gemologist Appraiser®

Expertise: Diamonds and Colored Gemstones.
Other Areas: Antique and Period Jewelry.


Sharrie Woodring Sharrie Woodring
Senior Gemologist, Gem Certification and Assurance Lab (GCAL)

Expertise: Diamonds and Colored Gemstones.