How to Read Diamond Inclusions on a Certificate

A diamond can have an excellent clarity grade and still show inclusions on its certificate. That is not a contradiction. Learning how to read diamond inclusions means understanding what the grading report records, where each feature sits, and whether it will affect the diamond’s beauty when worn.

For an engagement ring or fine jewellery purchase, the goal is rarely to find a technically flawless stone at any cost. It is to choose a certified diamond that looks clean, bright and well-proportioned for its shape, setting and budget. A clarity plot is one valuable part of making that decision with confidence.

What diamond inclusions actually are

Inclusions are internal characteristics formed while a natural diamond grew deep within the earth, or during the controlled growth process of a lab-grown diamond. They are the diamond’s individual identifying features. Common examples include crystals, feathers, clouds, needles and pinpoints.

A feature on the surface is usually called a blemish rather than an inclusion. This distinction matters because an internal feature near the centre of the stone may be more visible than a minor surface mark hidden beneath a claw. Both can appear in the clarity assessment, but they do not carry the same practical implications.

Inclusions are not automatically faults. Nearly every diamond has them, and many cannot be seen without magnification. Their impact depends on five factors: size, number, position, colour or contrast, and the way they interact with light. A small transparent crystal near the girdle is very different from a dark inclusion beneath the table.

How to read diamond inclusions on a clarity plot

Many GIA and IGI grading reports include a diagram called a clarity plot. It shows the diamond from the crown view, looking down through the table, and from the pavilion view, looking through the base. The plotted symbols indicate the approximate location and type of clarity characteristics observed by the grader.

Red markings commonly identify internal features, while green markings generally identify surface features on reports that use this convention. Always read the report’s key rather than relying on colour alone, as report formats may differ between laboratories and document types.

The plot is a map, not a photograph. It does not tell you the exact size, depth or visibility of an inclusion, and it is not drawn to a uniform visual scale. A prominent-looking symbol can represent a feature that is invisible to the naked eye. Equally, a very small symbol below the table may deserve closer review because its location makes it easier to notice.

Look first at the central table area. This is the broad, flat facet visible when the diamond is face-up, so inclusions here can be more apparent than comparable features near the girdle. Next, look at the arrows and symbols around the outline. These often show characteristics positioned at or beneath the girdle, where a suitable setting may make them far less noticeable.

If a plot contains several markings, do not assume the stone will look busy or imperfect. Graders plot all notable characteristics, even when the diamond is eye-clean. The assigned clarity grade reflects the combined effect of those features under 10x magnification, not simply the number of marks shown.

The most common plot symbols

A crystal is a mineral inclusion trapped within the diamond. A colourless crystal may have little visual effect, while a dark crystal can create contrast. Feathers are internal fractures or cleavage-like features. Small feathers are common, but a large feather that reaches the girdle or sits close to a point should be assessed carefully for durability.

Clouds are groups of tiny pinpoints. In many cases they are harmless, particularly when localised and faint. However, a significant cloud can sometimes reduce transparency or create a slightly hazy appearance. Needles are long, narrow crystals, while pinpoints are minute dot-like inclusions. Both are frequently unobtrusive.

Indented naturals and natural marks are remnants of the original rough diamond surface. They often sit around the girdle. Extra facets, polish lines and grain lines are typically surface-related finishing characteristics. Their importance depends on extent and placement, but they are often less concerning than an inclusion directly under the table.

Read the clarity grade with the plot, not separately

The clarity grade gives essential context to the diagram. It indicates how readily a trained grader can find the characteristics at 10x magnification.

Flawless and Internally Flawless diamonds are exceptionally rare, with no inclusions visible at 10x magnification in the latter category. VVS1 and VVS2 diamonds contain very, very slight inclusions that are extremely difficult to locate. VS1 and VS2 diamonds have very slight inclusions that are still usually impossible to see without magnification.

For many engagement-ring buyers, VS clarity offers a refined balance of rarity, beauty and value. SI1 diamonds can also represent outstanding value when the stone is eye-clean and the inclusions are positioned favourably. SI2 and I-clarity diamonds require more selective evaluation, as visibility and transparency can vary considerably from stone to stone.

This is where shape changes the decision. Round brilliant diamonds are particularly effective at disguising small inclusions because their facet pattern creates lively scintillation. Step-cut shapes such as emerald and Asscher cuts have broader, cleaner-looking facets, so clarity features can be easier to see. A VS2 emerald-cut diamond may therefore be preferable to an SI1 example, even where both grades might look equally attractive in a round brilliant.

Carat weight matters too. As a diamond becomes larger, its facets and table become larger, giving inclusions more visual space. A one-carat SI1 round can be beautifully eye-clean, while a larger three-carat SI1 may need more careful inspection. There is no single clarity grade that suits every diamond.

Which inclusions deserve closer attention?

The right question is not whether an inclusion exists, but whether it compromises appearance, structural integrity or long-term confidence. Pay particular attention to a dark or reflective inclusion under the table, a large cloud referenced as the grade-setting feature, or a feather extending from the girdle into the stone.

Features at vulnerable points deserve an informed setting choice. The pointed tip of a pear, marquise or princess-cut diamond is more exposed to knocks than the rounded edge of a round brilliant. If a feather, cavity or natural is located near that point, a protective V-shaped claw may be appropriate. This does not mean the diamond is unsuitable, but it should be matched to a setting that protects it well.

Also review comments on the report. Phrases such as “clarity grade based on clouds not shown” signal that the relevant feature may not appear on the plot. This wording does not automatically make a diamond a poor choice, but it is a reason to inspect high-quality imagery and seek specialist guidance. Transparency should be judged from the diamond itself, not from a diagram alone.

Use imagery and certification to confirm what the plot cannot show

A reputable grading report from an established laboratory provides an independent assessment of the diamond’s 4Cs, including clarity. For a significant purchase, match the report number to the diamond where possible and examine magnified photographs or video alongside the certificate.

Magnified imagery can make an inclusion look dramatic. A 20x or 40x image enlarges a pinpoint into something that appears substantial on screen. View the diamond at a normal face-up scale as well. Ask whether the feature is visible at normal viewing distance, whether the stone has strong transparency, and whether it remains attractive in ordinary lighting rather than only in studio photography.

For lab-grown diamonds, clarity plots and grading principles work in much the same way as for natural diamonds. The type of growth may influence the kinds of internal features observed, but the buying approach remains consistent: assess visible beauty, certification, cut quality and value together. Choosing lab-grown does not mean accepting lower standards; it gives you another route to exceptional size and quality.

Prioritise cut before chasing flawless clarity

A beautifully cut diamond can appear more vibrant than a higher-clarity stone with weaker light performance. Cut governs brightness, fire and scintillation, which are the qualities people notice first across a room. Clarity supports that visual performance when inclusions do not interrupt transparency or distract the eye.

A practical purchasing order for many buyers is to select the desired shape and carat weight, prioritise excellent cut and proportions, then choose the lowest clarity grade that remains convincingly eye-clean for that particular diamond. Colour, setting metal and personal preference then refine the selection. This approach often directs more of the budget towards the qualities that make a diamond look exceptional when worn.

An eye-clean SI1 round brilliant can be a stronger choice than a VVS diamond with less appealing cut, especially when the difference allows for a better carat weight, setting or wedding band. Conversely, a collector seeking exceptional rarity may reasonably value VVS or Flawless clarity. Luxury is personal, and the right specification should reflect both the wearer and the occasion.

A confident final check before you choose

Before committing, compare the clarity plot with the certificate grade, high-resolution imagery and the diamond’s face-up appearance. Confirm whether the key inclusion is central or near the edge, whether it is likely to be visible without magnification, and whether the chosen setting will offer suitable protection.

The best diamond inclusion is not necessarily one that is absent from the report. It is one that has no meaningful effect on the beauty, durability or confidence you feel each time the diamond catches the light.