Are you comparing two diamonds for an engagement ring in Montreal, with descriptions that look almost identical? A gemological report, often called a “diamond certificate,” helps explain their differences. Issued by a laboratory such as GIA or IGI, it describes the characteristics of the stone examined. However, it is neither an appraisal of its market value nor a guarantee that you will prefer it to another diamond. For a natural white diamond, here is what to check before comparing prices or choosing a setting.
Start with the report number and verify it directly on the issuing laboratory’s official website. The information displayed should match the document provided: shape, weight, measurements and grades. Also confirm that the report covers a natural diamond rather than a laboratory-grown diamond. When a laser inscription is listed, ask the jeweller to show it to you under magnification on the girdle, the stone’s outer edge. Keep in mind that a valid number alone does not prove that the diamond shown is the one described in the report. Matching its characteristics remains essential.
Carat measures weight, not width: 1 carat equals 0.20 grams. Two diamonds of the same weight can therefore look different on your hand. Check the measurements in millimetres, generally listed as length × width × depth. As a rough guide, a well-proportioned 1-carat round diamond often measures around 6.4 mm in diameter, though this is not an absolute rule. When comparing two stones of the same shape, focus on their face-up size and proportions rather than weight alone.
Colour in a natural white diamond is generally graded on the D-to-Z scale: D means no perceptible colour under the laboratory’s grading conditions, with yellow or brown tones becoming progressively more noticeable further down the scale. That does not mean you must choose D. Grades G or H can be worthwhile options to compare, depending on your sensitivity to colour and the setting. Ask to see the stones side by side under neutral lighting. Very intense store lighting can make the differences harder to assess.
Clarity describes internal inclusions and surface characteristics, assessed notably under 10× magnification. Grades range from FL to I3, with several intermediate levels, including VS1, VS2, SI1 and SI2. A VS2 or SI1 diamond is not automatically free of inclusions visible to the naked eye: the stone’s size, shape and inclusion locations matter a great deal. Ask whether a mark is visible from above at a normal viewing distance. An inclusion near a point or edge may also warrant checking for any effect on durability.
Cut, one of the 4Cs, refers to the quality of workmanship and proportions, not simply whether a diamond is round, oval or pear-shaped. For a round brilliant diamond, look for the overall cut grade when it appears on the report, then check polish and symmetry. These three elements are not interchangeable. For other shapes, the information and grading systems can vary by laboratory and report. Two “Excellent” ratings for polish and symmetry therefore do not guarantee exceptional sparkle. Viewing the stone in motion remains important.
Finally, read the fluorescence information and comments, even if they seem secondary. Fluorescence describes a diamond’s reaction to ultraviolet light; it is not automatically a flaw. Strong fluorescence does not necessarily mean the stone looks milky. Instead, ask whether its appearance changes under different lighting conditions. Comments may clarify certain characteristics, inscriptions or report details; any mention of treatment deserves a clear explanation. When comparing prices, make sure you compare more than four grades: measurements, actual appearance and individual characteristics matter too.
When it is time to choose, keep a short list of priorities: your budget for the stone, preferred shape, measurements and inclusions you are willing to accept. A report should inform your decision, not replace your eyes. At AUCLAIRE, centre diamonds are GIA- or IGI-certified, and every piece comes with an AUCLAIRE certificate of authenticity, separate from the gemological report. To move forward without getting lost in letters and numbers, consider asking the workshop for three certified natural diamond options suited to your budget, so you can compare their reports and measurements.
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