How to Read an IGI Diamond Grading Report

When reading an IGI report, always verify the top banner first. An IGI report will clearly specify whether the diamond is a Natural Diamond or a Laboratory Grown Diamond. It also states the unique report number and examination date. The report number corresponds directly to the official laboratory database. Make sure the report date is reasonably aligned with the stone's history.

The primary grading block details: • Shape and Cutting Style: e.g., 'ROUND BRILLIANT' or 'OVAL BRILLIANT'. • Measurements: Listed to the nearest hundredth of a millimeter (e.g., 7.42 - 7.38 x 4.54 mm). • Carat Weight: Expressed in decimal carats (e.g., 1.52 ct). • Color Grade: Letter grade from D to Z. • Clarity Grade: From Flawless down to I3. • Cut Grade: For Round Brilliants, IGI evaluates proportions to assign an overall cut grade (Ideal, Excellent, Very Good, Good, Fair). Note that on fancy shapes, this field is typically omitted.

Secondary grading parameters provide essential context on diamond craftsmanship: • Polish: Smoothness of the facet surfaces after polishing. Rated from Excellent to Poor. • Symmetry: Precision of facet alignment and facet junction intersections. • Fluorescence: Stone's visible reaction to long-wave ultraviolet light. Most diamonds exhibit 'None' or 'Faint', which is completely standard. • Inscription: Microscopic laser engraving on the girdle (e.g. 'IGI LG123456789'). This enables physical verification matching the document.

Never rely solely on a printed paper slip without verification. You can check any valid IGI report number directly on the official IGI website lookup portal. Important note on physical matching: Verifying that a report number exists in the laboratory database confirms that a report was issued with those specifications, but it does not independently verify that the physical stone in your hand is that exact diamond without matching its girdle laser inscription and physical millimeter measurements.