Diamond Colour Grading: Explained

When it comes to diamonds, most people are drawn to sparkle and size—but colour plays a vital role in how a diamond appears and how it's valued. Even a small difference in colour grade can change a diamond’s look, especially when set in certain metals or viewed in natural light.

In this guide, we explain how diamond colour grading works, what each grade means, and how to choose the right colour for your personal preferences, style, and budget.

What Is Diamond Colour?

In gemology, “diamond colour” refers to how colourless or tinted a white diamond appears. Most diamonds have a subtle yellow or brown tint due to trace elements like nitrogen. The less colour present, the rarer and more valuable the stone.

Colour is graded on a D-to-Z scale, developed by the Gemological Institute of America (GIA)—the global standard used by labs like GIA and IGI.

The GIA Diamond Colour Scale

Here’s how the D–Z scale works:

How Is Colour Graded in a Lab?

Grading is done in controlled lighting conditions, using master stones for comparison. Diamonds are examined face-down to minimise the brilliance that could hide colour.

At Diamond Lab, all lab grown diamonds are independently graded by IGI or GIA, with colour grades clearly listed on their certificates.

Does Diamond Colour Matter?

Yes—but how much it matters depends on your setting, diamond shape, and personal taste.

When Colour Is Most Important:

• In platinum or white gold settings (these metals highlight any yellow tint)

• In step-cut shapes like emerald or asscher, which have large, open facets that reveal more colour

• In larger carat sizes, where colour is easier to notice

When You Can Be More Flexible:

• In yellow or rose gold settings, where warmer tones blend nicely

• With brilliant cuts (like round, oval, or radiant), which reflect more light and mask colour

• If prioritising size or clarity on a budget

💎 A popular, balanced option?
👉 Solara Oval Half Bezel Ring, which pairs beautifully with D–H colour grades in both warm and cool metals.

Lab Grown Diamonds & Colour

Lab grown diamonds often have better colour grades than mined diamonds because of the controlled growth environment. Most lab diamonds sold today are in the D–F (colourless) or G–H (near colourless) ranges.

Still, lab diamonds can have colour variations depending on the method used:

• CVD diamonds may show brown or grey undertones (corrected through post-growth treatment)

• HPHT diamonds often produce brighter, whiter stones

Every lab diamond sold at Diamond Lab includes IGI or GIA certification detailing the exact colour grade.

What About Fancy Coloured Diamonds?

The D–Z colour scale applies only to white (colourless to tinted) diamonds.
Fancy coloured diamonds—such as pink, yellow, or blue—are graded on an entirely different scale based on:

• Hue – the dominant colour

• Tone – how light or dark it is

• Saturation – how intense the colour is

Fancy coloured diamonds (including lab grown versions) are graded as Fancy Light, Fancy Intense, Fancy Vivid, and so on.

Tips for Choosing the Right Colour

1. Match metal to stone:

   • D–F for white metals (platinum, white gold)

   • G–J pairs well with yellow or rose gold

2. Consider size & cut:

   • Bigger diamonds show more colour

   • Brilliant cuts hide colour better than step cuts

3. Balance with budget:

   • Dropping one grade (e.g., from F to G) can save hundreds, with little visible difference

4. View in person or with guidance:

   • Lighting affects how colour is perceived

   • Always compare against similar stones when possible

Final Thoughts: What Colour Says About Your Diamond

Diamond colour is about more than just science—it’s about style. A D colour may be icy and modern, while a J colour might offer a warm, vintage aesthetic. Understanding how colour grading works empowers you to choose what looks best to you, not just what scores highest on paper.

Still Unsure? We’re Here to Help

Book a consultation at Diamond Lab to compare colour grades side-by-side, view certified lab diamonds, and choose the perfect stone for your custom design.

📍 Contact our Perth showroom or schedule a virtual appointment.