Start looking at diamonds and you quickly find yourself comparing letters, numbers and percentages.

D or F colour. VVS or VS clarity. Excellent cut. 1.4 or 1.5 carats.

So, what actually matters when choosing a diamond?

The 4Cs — cut, colour, clarity and carat — are the starting point. They tell you important things about a diamond's quality, but they don't always tell you everything about how an individual diamond will look.

Understanding what each grade means, and then looking beyond the grades, can make comparing diamonds much clearer.

The 4Cs: cut, colour, clarity and carat

Cut describes how well a diamond's facets and proportions work together with light. A well-cut diamond manages light effectively, creating brightness, fire and scintillation.

Brightness is the white light reflected from the diamond. Fire is created when white light disperses into flashes of colour. Scintillation is the pattern of light, dark and sparkle you see as the diamond, light or viewer moves.

Colour is graded from D to Z. At the upper end, D–F is Colourless, while G–J is Near Colourless. Differences between neighbouring grades can be subtle, particularly at the top of the scale, but they represent real distinctions in colour quality.

Clarity describes inclusions inside a diamond and blemishes on its surface. The scale runs from Flawless (FL), through VVS, VS and SI, to Included (I). The grade considers their size, number, type, position and how noticeable they are under 10× magnification. Generally, the fewer and less noticeable these features are, the higher the clarity grade.

Carat is a measure of a diamond's weight, not simply its visible size. Two diamonds with the same carat weight can have different dimensions and proportions, so they may not look exactly the same.

Looking beyond the diamond grades

The 4Cs give you a strong starting point, but two diamonds with similar grades aren't necessarily identical.

With clarity, for example, two VS1 diamonds have the same clarity grade, but their inclusions can be different. One might have a small inclusion towards the edge of the diamond, while another has one closer to the centre. The type, size and position all form part of the assessment.

Proportions can also change how a diamond looks. An oval diamond can appear shorter and rounder or longer and more elongated depending on the relationship between its length and width. Pear diamonds can similarly range from fuller, softly rounded shapes to longer, more slender silhouettes.

Proportions can affect both the shape of the diamond and how it handles light, which is why the numbers are useful guidance rather than a formula.

What does a diamond grading report tell you?

A diamond grading report provides independently assessed information about the diamond. Depending on the report, this can include the 4Cs, measurements, proportions, polish and symmetry.

The grading report gives us the technical picture, while imagery or video helps us look at the individual diamond.

The available imagery or video can help us assess its outline, facet pattern and visible inclusions — details that a list of specifications alone can't always show.

Together, the grading report, specifications and imagery give us a fuller picture of the diamond we're considering.

When we source diamonds, we consider all of this information together and take you through the differences clearly — including why one diamond may cost more than another.

So you're not simply choosing between grades. You understand the diamond behind them.