Lab-Grown Diamonds · The Science

Fancy Coloured Diamonds: Black, Blue, Pink & Yellow Explained (2026)

By Tushar Leclerc · 8 min read

Last Updated: September 12, 2026

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Most diamonds are graded on how little colour they have, the D-to-Z white scale. Fancy coloured diamonds are the exception: stones with enough colour to fall outside that scale entirely, prized for the very thing a white diamond is graded down for. This guide explains what they are, how each colour happens, and what they cost, straight, without the auction-house mystique.

What are fancy coloured diamonds?

A fancy coloured diamond is a real diamond, pure crystalline carbon, that displays a noticeable body colour. Where a white diamond is graded from D (colourless) to Z (light tint), anything with more colour than Z is graded on a separate "fancy" scale, from Faint through to Fancy Vivid and Fancy Deep.

They occur in nearly every colour: yellow and brown are the most common, while blue, pink, green and red are extraordinarily rare. The key difference from a white diamond is that for fancy colours, more colour means more value, the opposite of the white scale. A vivid, saturated colour is rarer and costs more than a faint one.

How each colour forms

A diamond gets its colour from something interrupting its pure carbon structure during growth, either a trace element or a structural distortion. The cause differs by colour:

• Yellow comes from nitrogen atoms in the crystal, absorbing blue light and leaving a yellow cast. Nitrogen is common, which is why yellow is one of the more available fancy colours.
• Blue comes from boron, which is rare in the diamond-forming environment, making natural blue diamonds exceptionally scarce. The Hope Diamond is the famous example.
• Pink and red are not caused by an element at all but by a distortion in the crystal lattice that changes how it absorbs light. The exact mechanism is still debated, and pink is among the rarest and priciest of all.
• Green usually comes from natural radiation exposure deep in the earth over millions of years, altering the stone's surface structure.

Fancy colours can also be grown in a lab, by introducing the same elements (such as nitrogen for yellow or boron for blue) during CVD or HPHT growth, or created by treating an existing diamond. Our guide to how lab-grown diamonds are made covers those growth methods in full.

Are coloured diamonds real?

Yes. A fancy coloured diamond, whether yellow, blue, pink or black, is a genuine diamond with the same hardness of 10 and the same crystal structure as a colourless one. The colour does not make it any less of a diamond; it simply reflects what happened during its formation.

This holds for both natural and lab-grown coloured diamonds. A lab-grown blue diamond is as real as a mined one, grown with boron rather than having boron present by geological chance. The only thing a reputable certificate will always state is whether the colour is natural or the result of treatment, because that distinction drives the price enormously.

Rarity and price by colour

Natural fancy coloured diamonds are among the most expensive gems on earth, far beyond white diamonds of the same size, precisely because the geological conditions that create them are so rare. A rough ranking, from more available to almost unobtainable:

This is why a famous natural pink or blue can sell for tens of millions at auction. Lab-grown fancy colours, by contrast, are far more affordable, because the colour can be produced reliably rather than waited on from geology, the same economics that make white lab-grown diamonds a fraction of mined prices.

Black diamonds, explained separately

Black diamonds deserve their own note, because they are coloured differently from the rest. A black diamond is a real diamond, but its colour does not come from a trace element. It comes from a very high concentration of dark inclusions, usually graphite, scattered so densely through the stone that it reads as opaque black rather than clear.

Because of those inclusions, black diamonds do not sparkle the way a white or other fancy diamond does; they have a metallic, almost matte lustre instead. They have become popular in men's jewellery and in alternative, modern designs for exactly that bold, dark look. Natural black diamonds exist, and treated black diamonds (ordinary diamonds heated to blacken them) are common and far cheaper, so certification matters here too.

What Riona makes

To be straight with you: Riona specialises in white lab-grown diamonds, not fancy colours. We think the clearest value in the market today is a brilliant, colourless, IGI-certified lab-grown diamond in solid gold, at a fraction of the mined price, and that is what our whole collection is built around.

If a fancy colour is what you are set on, a specialist coloured-diamond dealer is the right place to look. But if you came here weighing a coloured stone mainly to stand out on a budget, it is worth seeing what a well-cut white lab-grown diamond looks like first, the saving over mined often buys a noticeably larger or higher-grade stone than a coloured equivalent would.

Round SolitaireFrom $1,288 Oval HaloFrom $1,530 Emerald SolitaireFrom $1,369 Cushion SolitaireFrom $1,369 Diamond StudsFrom $1,126

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