IGI Certified Lab-Grown Diamonds: How to Read Your Report

Check the description before comparing grades. The report should identify the diamond as laboratory-grown. The IGI name alone does not establish origin: IGI examines natural diamonds, laboratory-grown diamonds and other gemstones.

IGI describes a screening process that distinguishes natural, laboratory-grown and simulant material. Its grading workflow also uses identification numbers to conceal owner information from graders. These procedures support identification and assessment; they do not mean that every graded diamond receives the highest grades. IGI’s grading process

Next, establish what was examined. A report for an individual loose diamond and a report for a completed ring have different scopes. If you are choosing a centre stone, ask which document describes that particular diamond and whether it was assessed before or after mounting.

Begin with the identifying details, then read the grading results and supporting information together. IGI’s report-reading guide describes the main fields and notes that reports may include proportion diagrams and clarity plots.

Do not rely on a cropped screenshot containing only colour, clarity and carat weight. Request the complete document so that qualifications, comments and identification details remain visible.

Carat measures weight: one carat equals 0.2 grams. It does not specify a diamond’s visible diameter or length. Two diamonds with the same weight can have different dimensions and appear different in size. IGI’s carat-weight guide

When comparing stones, place their millimetre measurements beside their carat weights. For an elongated shape, look at both length and width. A longer stone is not necessarily wider, and an impressive length alone may not describe the appearance you want.

For example, an illustrative oval measuring 10.00 × 7.00 mm has a length-to-width ratio of approximately 1.43. That calculation describes its outline; it does not establish its cut quality.

Also distinguish an individual diamond’s weight from a jewellery listing’s total diamond weight. Ask for the centre-stone weight separately when a ring includes surrounding diamonds. This prevents you from comparing a complete ring’s combined weight with another listing’s single centre stone.

For diamonds in the normal colour range, IGI uses the D–Z scale. D–F belongs to the colourless category, while G–J is near-colourless. Fancy-colour diamonds use a different assessment framework. IGI evaluates normal-range colour under controlled conditions, using comparison stones. IGI’s colour guide

The grade and a photograph answer different questions. A report records the laboratory assessment; a photograph shows the diamond under particular lighting, camera settings and surroundings. IGI notes that shape, cut, mounting and lighting can affect perceived colour.

When comparing shortlisted diamonds, request images or videos taken under similar conditions. If the setting metal is already chosen, discuss how each stone looks in that context.

There is no need to select a colour grade solely because it is the highest available. Decide whether the difference matters to your eyes, your design and your budget.

IGI assesses clarity at 10× magnification, considering characteristics such as their size, position, nature and visibility. Its scale includes Internally Flawless, VVS, VS, SI and Included categories. A grade describes the assessment under magnification; it is not a photograph of what you will see during everyday wear. IGI’s clarity guide

Ask where the relevant characteristics are located and whether they are noticeable without magnification. A seller’s “eye-clean” description should come with an explanation of the viewing conditions, including distance, lighting and whether the stone was examined face-up.

If the report includes a clarity plot, use it to guide those questions. Ask the seller to point out the corresponding areas in a magnified video. This makes the discussion more useful than asking whether a clarity grade is simply “good”.

Keep the viewing scale in mind, too. An inclusion that looks prominent in an enlarged image should also be assessed at a realistic viewing size. Conversely, a distant photograph may not provide enough detail to answer your questions.

These fields describe related but different aspects of craftsmanship. Polish concerns the finish of the facet surfaces. Symmetry concerns the alignment and arrangement of the diamond’s features. Neither field, by itself, establishes an overall cut grade. IGI’s terminology glossary

For a round brilliant, read the actual cut grade recorded on the report, then examine the supporting proportions and finish grades. If a retailer uses an additional description such as “premium”, ask how it relates to the laboratory’s assessment.

IGI also offers cut grading for fancy-shaped diamonds. It is optional, so an overall cut grade will not necessarily appear on every fancy-shape report. IGI’s grading process

Its fancy-shape method combines finish assessment, proportion checks, shape-specific craftsmanship requirements and light-return assessment. The scale runs from Excellent to Poor. Proportions alone are insufficient, and IGI distinguishes its fancy-shape light-return assessment from a full assessment of fire and scintillation. IGI’s cut-grading methodology

Consequently, an oval with Excellent polish and Excellent symmetry should not automatically be described as having an IGI Excellent overall cut grade. Check whether that separate grade is actually present.

Use the report to narrow your shortlist, then compare the stones in motion. Ask for a slow video that lets you examine the centre, edges and changing pattern of bright and dark areas.

Illustrative sample. Check the actual diamond and its laboratory document.

A proportions diagram can help you understand how the diamond’s weight is distributed. Table size, depth and other recorded measurements provide additional context, but a single percentage should not become a substitute for assessing the entire stone.

When a seller recommends a diamond because of its proportions, ask them to explain the recommendation using the report and the actual video. This connects the numbers to something you can evaluate.

Fluorescence describes a diamond’s reaction to ultraviolet light. It is a separate characteristic from colour and clarity. IGI’s explanation of fluorescence assessment

If fluorescence is relevant to your shortlist, ask to see the diamond under appropriate viewing conditions. Avoid drawing conclusions about overall beauty from that field alone, or assuming that a fluorescence entry answers every question about transparency and appearance.

A report may contain information about the growth process or subsequent treatment. IGI states that the growth process and presence of treatments can be included in the comments section upon request. This information should therefore be checked on the particular document rather than assumed to appear on every report. IGI’s laboratory-grown reporting service

Growth-method information describes how the diamond was created. Treatment information addresses a separate question about processing. Read the complete wording instead of interpreting a short abbreviation in isolation.

If the seller makes a specific claim about growth method or the absence of treatment, ask what documentation supports it. A blank comments section is not sufficient evidence for an “untreated” claim.

You can ask: “Does the report explicitly support this description, or is there additional documentation I should review?” This keeps the discussion tied to the individual stone.

Verification involves checking both the document and its connection to the stone being offered. Looking up a report number checks an online record; it does not physically examine a diamond.

Open IGI’s official report-verification page and enter the report number yourself. Compare the result with the complete report supplied by the seller.

Check the description, shape, measurements, carat weight, colour, clarity and any relevant comments. Compare these details with the listing as well. If a listing rounds a measurement or uses a different description, ask for clarification before treating the records as a match.

Keep a copy of the report alongside the listing and order details. This gives you a consistent set of references when discussing the purchase.

IGI’s Laserscribe service places identifying characters on a diamond’s girdle, its outer edge. A report-number inscription helps connect the stone to its documentation. IGI’s inscription service

Ask a jeweller or gemmologist to examine the inscription under magnification and compare it with the report’s inscription entry. They can also compare accessible measurements and other identifying features.

If the diamond is mounted and the inscription cannot be seen clearly, ask what can be checked without disturbing the setting. Do not assume that an unsuccessful viewing attempt proves the inscription is absent.

If a number, measurement or description does not agree, request a clear explanation and the correct documentation. An unsuccessful online lookup should also be resolved with the seller or IGI.

Pause the purchase while a material mismatch remains unresolved. A convincing photograph of a report should not replace a consistent connection between the document, the listing and the stone.

Illustrative sample. Check the actual diamond and its laboratory document.

IGI also issues reports for finished jewellery. These describe the article and its gemstones, with assessments made within the limits of the mounting.

IGI explains that where grading is performed as the mounting permits, colour and clarity may be expressed as ranges, and cut may be estimated. Where a stone was graded before mounting, the report can state that and use the corresponding grading information. IGI’s jewellery-report guidance

A range such as D–E should therefore be read as a range. It should not automatically become “D colour” in a product description.

For a ring with several diamonds, establish which entries apply to the centre stone and which describe accompanying stones. Ask whether the centre has its own loose-diamond report and whether the jewellery document refers to it.

This distinction is especially useful when comparing a loose stone with an already completed ring. Before comparing specifications, make sure you understand how each set of grades was obtained.

Consider an illustrative listing for a 2.00 ct oval with F colour, VS1 clarity and measurements of 10.00 × 7.00 × 4.40 mm. These are example figures, not an offer of Uniglo stock.

The weight tells you its mass. The measurements describe its dimensions. The colour and clarity grades give you laboratory assessments. You would still need to check whether an overall cut grade is recorded, review any comments, verify the report and examine the diamond’s appearance.

Now imagine a second listing with the same carat weight, colour and clarity. You should still compare the dimensions, available cut information, images and documentation before deciding that the two stones are equivalent.

A useful shortlist keeps each diamond’s report, video and quotation together. When something is missing, write down the unanswered question rather than filling the gap with an assumption. This makes it easier to compare the actual options.

A grading report does not set the diamond’s selling price or promise a future resale amount. An appraisal is a separate type of document that addresses value for a stated purpose. IGI distinguishes its appraisal services from its grading reports. IGI’s appraisal information

Likewise, laboratory-grown origin does not by itself document a producer’s energy use or substantiate a specific environmental claim. If those factors matter to your purchase, request supporting evidence for the claim being made. IGI’s educational guidance discusses the need for separate sustainability credentials. IGI’s lab-grown diamond guidance

Treat the report as one part of the purchase documentation. The quotation, sales terms, physical inspection and any additional claims each need their own supporting information.

When enquiring about a diamond, share your preferred shape, approximate carat range, budget and any report requirements. Ask for the complete IGI report for the specific stone, its current availability and images or video that help answer your remaining questions.

You can explore the lab-grown diamond inventory or use our loose lab-grown diamond guide when planning a custom piece.

Jewellers and trade buyers can visit our IGI-certified lab-grown diamond wholesale page for enquiries about commercial sourcing.