IGI or GIA: which report your diamond should have

A diamond’s passport: what it records

A grading report is issued by an independent gemological laboratory. The stone is examined by specialists who sell nothing, so the jeweler has no say in the grade. They measure it to a hundredth of a millimeter, study it under a microscope and record:

• carat weight;
• color, on a scale from D (completely colorless) to Z;
• clarity, from FL (no inclusions even at tenfold magnification) to I3;
• cut, along with polish and symmetry;
• fluorescence;
• the stone’s origin and, for lab-grown diamonds, the growth method.

The report number is laser-inscribed on the girdle, the thin band around the edge of the stone. It can’t be seen without magnification, yet it ties the diamond to its document for life.

GIA: the laboratory that created the language of diamonds

The Gemological Institute of America was founded in 1931. GIA created the 4Cs (carat, color, clarity, cut) and the D-to-Z color scale. Every diamond in the world is now described with them.
For natural stones, a GIA report is still the benchmark. Auction houses and dealers look to it first. A natural diamond with a GIA report usually costs more than a similar stone graded by another lab.

IGI: the Antwerp laboratory that believed in lab-grown diamonds first

The International Gemological Institute was founded in 1975 in Antwerp, the city where Europe’s finest stones have been cut and traded for centuries. Today IGI runs around thirty laboratories worldwide, in New York, Mumbai, Hong Kong, Dubai and beyond.
IGI has certified lab-grown diamonds since 2005, earlier than most of its peers. Since then it has become the leading laboratory for the category. Most of the world’s lab-grown diamonds are sold with IGI reports.

Which report to choose

Considering a natural diamond over one carat as an investment? Choose a GIA report. It’s the easiest one to stand behind when you resell.
Looking for a lab-grown diamond for an engagement ring, earrings or an everyday piece? An IGI report tells you more about the stone: its exact color, clarity, cut quality and growth method.
Either way, the report must be original and tied to that specific stone. A “store certificate” can’t replace an IGI or GIA report. Neither can a document from a laboratory you can’t find anything about.

How to verify an IGI report

• Find the report number on the certificate. For a lab-grown stone, it starts with the letters LG.
• Enter the number in the Verify Your Report section on igi.org. The online record should match the paper document.
• Check the laser inscription on the girdle. Under a loupe, the number on the stone should match the number on the report.
• Compare the details: weight, shape and measurements in millimeters.