GIA, the Gemological Institute of America, is a public benefit, nonprofit institute established in 1931. It works in gem research, education and laboratory grading.
In more detail
GIA established the 4Cs and the International Diamond Grading System. It runs laboratories and schools in several countries. It publishes the scientific journal Gems & Gemology. Its laboratory is a member of the LMHC, the group that standardizes colored stone report wording.
Related terms
- Four Cs: The four Cs are color, clarity, cut and carat weight: four scales that describe the quality of a diamond. GIA made them into a grading system in the 1950s.
- Diamond grading report: A diamond grading report is an independent lab's record of what a stone is and how it grades. It is true for the day the lab examined the stone.
- Report Check: Report Check is GIA's online database. Enter a report number to see what GIA itself recorded; IGI's equivalent is Verify Your Report.
- Cut grade: The cut grade rates how well a diamond's proportions and finish work, from Excellent to Poor. GIA gives it only to standard round brilliants in the D-to-Z color range.
- Colored stone report: A colored stone report is a lab document that identifies a gem and states any treatment the lab detects. GIA's identification report describes the color but does not grade it.