Every IGI certified diamond arrives with one sheet of paper that most buyers glance at once and never open again. That is a mistake. The report is the only objective account of what you actually bought, and it takes about ninety seconds to read properly.

Lab-grown stones are no longer a niche choice, which makes the grading report the single most useful document in the box. It tells you the color, the clarity, the cut quality, how the crystal was grown, and whether anything was done to it afterward. Learn the fields once and you can evaluate any stone, anywhere, without taking a seller's word for it.

Those numbers come from three places. The Knot Worldwide's 2026 Real Weddings Study found that 61% of engagement rings now have a lab-grown center stone, a 239% increase since 2020. IGI states that it has been grading laboratory grown diamonds since 2005, after fifty years serving the trade. And industry analyst Sherry Smith of The Retail Smiths, reporting in National Jeweler, put the growth in lab-grown finished engagement ring sales at 31% while natural diamond sales fell 4%.

What an IGI Certified Diamond Report Actually Lists

An IGI laboratory grown diamond report documents thirteen specific things about one stone, and nothing about the ring it sits in. Everything on the page describes the diamond itself, which is why the report travels with the stone rather than the setting.

• Report number. A unique identifier beginning with LG for laboratory grown stones.
• Shape and cutting style. For example Round Brilliant, Emerald, or Pear.
• Measurements. Millimeter dimensions, given as minimum to maximum diameter by depth.
• Carat weight. Recorded to two decimal places.
• Color grade. On the same letter scale used for natural diamonds.
• Clarity grade. From Flawless down through the Included range.
• Cut grade, polish, and symmetry. Three separate finish assessments.
• Fluorescence. The stone's reaction under ultraviolet light.
• Growth method. HPHT or CVD, noted in the comments.
• Post-growth treatment. Disclosed in the comments, or recorded as As Grown.
• Laser inscription. The report number, written microscopically on the girdle.
• Diamond type. A gemological classification such as Type II.
• Proportion diagram. Table percentage, depth percentage, and crown and pavilion angles.

Every piece in our tennis bracelet line is built from stones carrying this paperwork, from the Opale Round Diamond Tennis Bracelet (from $550) to the Aurore Round Diamond Tennis Bracelet (from $1,450), which pairs IGI certification with Roomy's own quality check before the piece ships.

The Four Grades That Move the Price

Color, clarity, cut, and carat weight account for nearly all of the price difference between two diamonds of the same shape. The table below is the honest version of what each grade buys you and where the money stops working hard.

GIA's own buying guidance explains the structure behind all four, including that it created the D-to-Z color grading scale and that a clarity grade of Flawless means no inclusions and blemishes are visible at 10x magnification. If you want the clarity letters in more depth, our diamond clarity chart explainer walks through where VS1 and VS2 genuinely differ. These grades matter most in step cuts, where an open table leaves nothing disguised, which is exactly the trade-off we unpack in our edit on emerald cut diamonds.

Growth Method, Treatment, and the Line Most Buyers Skip

The comments section is the most informative part of an IGI report and the part almost nobody reads. It is where the laboratory records how the crystal was grown and whether it was altered afterward.

Lab-grown diamonds are produced one of two ways. High Pressure High Temperature, abbreviated HPHT, recreates the conditions found deep in the earth. Chemical Vapor Deposition, abbreviated CVD, builds the crystal layer by layer from a carbon-rich gas. Neither method is inherently better, and both produce real diamond with the same hardness and the same optical properties.

What matters more is the treatment line. When a report reads As Grown, no indication of post-growth treatment, the color and clarity on the page are the result of the growth process alone. When a stone has been processed after growth, usually to improve its color, IGI discloses that in the same section. Two stones can share a color grade and have arrived there by very different routes, and only the comments tell you which.

IGI has been explicit about applying one standard across both categories. The institute stated in July 2025 that it "will continue applying the universal 4Cs grading to all diamonds, whether natural or lab-grown", rather than scoring lab-grown stones on a shortened scale. That matters when you compare reports: a VS1 should mean the same thing on both pages.

Fluorescence appears on the report as well, and it is far less alarming than its reputation suggests. We covered where it helps and where it hurts in our guide to diamond fluorescence.

How to Verify an IGI Report in Under a Minute

Verification takes one number and one website. Enter the report number into the Verify Your Report tool at igi.org and compare what the database returns against the paper copy in your hand, field by field.

The same number is laser-inscribed on the diamond's girdle, the thin band around its widest point, in text far too small to read without magnification. Any jeweler can show it to you under a loupe or microscope at 10x. If the inscription, the paper, and the database agree, the stone in the setting is the stone on the report.

Certification is also what makes a piece insurable at the right value. A documented stone with a verifiable report number gives an appraiser something concrete to work from, whether that is the Linear Diamond Half Eternity Band (from $700), the Oval Diamond Solitaire Pendant (from $2,000), or the Starlight Portal Diamond Stud Earrings (from $1,500). Keep the report with your insurance paperwork rather than in the jewelry box, and photograph it once so a replacement claim never depends on finding the original.

Frequently Asked Questions