Established in 1975, the International Gemological Institute (IGI) is the largest independent gemological laboratory in the world, with locations in all major diamond trade cities. The IGI's mission is to provide the industry's professionals and consumers with accurate, reliable expertise through education programs and through diamond and fine jewelry certification.
Each diamond is scientifically analyzed by several gemologists, who combine their experience with state-of-the-art equipment to produce a precise description of the characteristics of the diamond and the quality of its cut.
A diamond's carat weight and measurements are taken using carefully calibrated instruments.
The color of a diamond is based on a scale from D (colorless) to Z (yellow) by comparing it to master stones of predetermined color. The amount of fluorescence is noted on a scale from None to Strong.
A diamond's clarity is assigned by an expert gemologist using a special scope and a 10x magnification loupe. Clarity is determined on a scale ranging from IF (internally flawless) to I3 (imperfect or heavily included). The stone's characteristics are plotted on a diamond diagram.
A diamond's finish includes such factors as polish, symmetry, and proportions. Assigned a grade from Excellent to Poor, polish and symmetry are evaluated based on the quality of the polish and the precision of the cutting details.
Proportions are evaluated based on the execution of the cutter's design, rating factors such as table diameter, crown height, pavilion depth, girdle thickness, and culet size, and is assigned a grade from Excellent to Poor.
The IGI Diamond Report contains a detailed analysis of the stone's characteristics, including carat weight, color, clarity, polish and symmetry, and proportions. A diamond diagram with plotted clarity characteristics is also included.
The IGI Diamond ID is a passport-sized document that contains the same detailed information as the Diamond Report, without the plotted diagram. This report is also available in a more compact credit card size.