Diamond certification, decoded

Why independent grading matters

A grading report answers the only question that matters when you cannot yet see the stone in person: how do you know? Independent gemological laboratories exist so that the party selling a diamond is never the party grading it. A trained gemologist who has no stake in the sale examines the stone under controlled lighting and magnification, records what is actually there, and puts it in writing.

Every Everfire diamond arrives with a report from an independent laboratory, about four in five from IGI, the rest from GCAL. Each stone we source is an individual, and its report is its permanent record: the document that lets you compare, insure, and one day upgrade it with confidence.

What a grading report contains

The heart of any report is the 4Cs, carat, color, clarity, and cut, the four measures that together describe a diamond's weight, whiteness, purity, and light performance. But a full report goes further, and the supporting details are often where the story lives. They explain why one stone throws more fire than another of the same weight and grade.

Beyond the 4Cs, expect to find:

• Measurements, length, width, and depth in millimeters, recorded to the hundredth
• Table and depth percentages, the proportions that govern how light enters the stone and how much of it returns to your eye
• Polish and symmetry, how precisely the facets were finished and aligned
• Fluorescence, how the stone responds to ultraviolet light, from None to Very Strong
• Growth method, whether the diamond was grown by CVD or HPHT
• Treatment disclosure, whether the stone received any post-growth treatment, or is presented as grown

The inscription on the girdle

Nearly every certified lab-grown diamond carries a laser inscription on its girdle, the thin rim where the crown meets the pavilion. It is microscopic, invisible to the naked eye, and easily read under about 20x magnification, which any jeweler can provide in a minute.

The inscription matches the report number, permanently tying the physical stone to its paper. It also identifies the diamond as lab-grown for life, which is exactly as it should be. Transparency is not a concession; it is the standard.

IGI: the working standard for lab-grown

The International Gemological Institute grades the large majority of the world's lab-grown diamonds, and its reports are the lingua franca of the category. An IGI report gives you full letter grades: color on the D-to-Z scale, clarity from Flawless through Included, and a cut grade, the same vocabulary used for mined stones, applied with the same rigor.

IGI report numbers run nine to ten digits and can be verified in seconds on IGI's website. On lab-grown stones, IGI's girdle inscription begins with the letters LG, followed by the report number.

GCAL: cut quality, guaranteed

Gem Certification and Assurance Lab is a smaller, quality-focused laboratory known for the rigor of its analysis and for standing behind its grading. Its reports include detailed light-performance documentation alongside the standard grades.

GCAL is best known for its 8X cut grade, awarded only when a stone earns the top mark across eight separate cut-quality criteria. One thing to know: 8X applies to round brilliants only. For a round stone chosen for maximum fire, it is one of the most demanding cut certifications available. Fancy shapes, ovals, emeralds, pears, are graded on the other measures, since 8X's criteria are defined for the round brilliant's geometry.

Where GIA fits

The Gemological Institute of America remains the historic authority on mined diamonds, and its standards shaped the 4Cs themselves. But in late 2025, GIA moved lab-grown diamonds to a simplified system that describes them as Premium or Standard, without full letter grades for color and clarity.

A two-tier label cannot tell you whether a stone is D or F color, VS1 or VVS2, distinctions that meaningfully affect both beauty and price. This is why most retail lab-grown inventory today carries IGI or GCAL reports, and why Everfire uses those two laboratories. You deserve the full vocabulary, not a summary.

How to verify your report

Verification takes minutes. Enter the report number into the issuing lab's online database and confirm the details match your document. Have the girdle inscription read under magnification and confirm it matches the report number. Check that the stone's measurements agree with the report to the hundredth of a millimeter.

Every Everfire diamond ships with its original report, and the stone in the box matches the paper, that is the whole point of certification. If anything about your diamond is not what you expected, our 30-day free insured returns mean the decision always remains yours.