Are coloured lab-grown diamonds real? Pink, yellow, blue and black

Quick answerUpdated October 17, 2026

Yes, coloured lab-grown diamonds are real diamond. GIA says nitrogen turns diamond yellow and boron added during growth makes it blue, while pink CVD stones get their colour mainly from irradiation and annealing after growth. The grading report can say how the stone was grown and whether it shows signs of treatment after growth.

Are coloured lab-grown diamonds real diamonds?

Yes. A coloured lab-grown diamond is diamond grown in a factory, by HPHT (high pressure, high temperature) or CVD (chemical vapour deposition), with something in the crystal that gives it colour. GIA’s guide to the two growth methods sets out the basics: nitrogen “turns diamonds yellow”, so growers had to keep it out to make colourless stones; adding boron during growth gives blue crystals; and other colours, such as pink and red, can be produced by treatment after growth. Early HPHT stones were often yellow or yellow-orange from nitrogen, but most HPHT stones are now colourless: GIA says more than 90% of the HPHT diamonds it received from 2021 to 2023 were colourless. Of the several hundred CVD stones GIA examined from 2003 to June 2016, 60% were colourless to near-colourless or very light brown (D to N) and 24% were in the pink range, the largest coloured group. The colours GIA describes come from atoms and defects in the diamond crystal itself. That is different from the surface coatings found on some coloured moissanite. How the two growth methods work is explained in CVD vs HPHT.

What makes a lab-grown diamond pink, yellow, blue or black?

Each colour has its own cause, and some are grown in while others are added after growth. The last column quotes the comments on IGI reports we looked up; each is one stone, not a rule.

Colour	What causes it (GIA)	Grown in or added after growth?	What one IGI report says
Yellow	Isolated nitrogen in the crystal. Early HPHT stones were often yellow or yellow-orange from it, and GIA also describes CVD stones coloured yellow by nitrogen	Usually grown in	0.30 ct Fancy Vivid Yellow, HPHT, April 2026: “As Grown - No indication of post-growth treatment”
Blue	Boron added during growth. Blue HPHT stones deliberately doped with boron were among the first gem-quality lab diamonds. GIA has also graded a few blue CVD stones coloured by irradiation	Either	0.93 ct Fancy Vivid Blue, CVD, September 2025: “Indications of post-growth treatment”
Pink, red, orangy and purplish pink	Nitrogen-vacancy (NV) centres. In pink CVD stones, GIA says the colour is mainly the result of annealing and irradiation after growth	Usually added after growth	0.70 ct Fancy Pink, CVD, February 2025: “Indications of post-growth treatment”
Green	High amounts of nickel in HPHT growth, though only a few saturated green HPHT stones have been submitted to GIA; irradiation after growth can also give a greenish colour	Either	None looked up
Black	Not explained in the GIA research cited here	Not known from these sources; ask	0.95 ct Fancy Black, CVD, September 2025: “Indications of post-growth treatment”

The report numbers, in the same order, are LG788641587, LG733563967, LG680510073 and LG731580548. Type one into igi.org to see the full report. GIA’s 2024 review also notes that gem labs have documented a few natural diamonds coloured greenish blue by a boron-doped CVD layer under 0.1 mm thick grown over them, so read a blue stone’s report closely.

Are pink lab-grown diamonds treated?

Usually. Pink in these stones comes from nitrogen-vacancy (NV) centres, where a nitrogen atom in the crystal sits next to a vacancy, a missing carbon atom. GIA’s 2016 review of the CVD diamonds it had examined says the colours of its pink samples were mainly the result of annealing and irradiation after growth, starting from light brown crystals, and describes multiple treatments: HPHT annealing, irradiation and low-temperature annealing. GIA adds that brownish pink stones were occasionally as grown. Both IGI pink reports we looked up, a 0.70 ct Fancy Pink (LG680510073) and a 0.20 ct Fancy Intense Pink (LG724565667), name CVD growth and note “Indications of post-growth treatment”. A treated pink lab diamond is still diamond. GIA says most pink CVD stones are treated after growth to create high concentrations of NV centres, which are defects in the crystal, so the colour is in the diamond, not in a surface coating. Those centres also show under ultraviolet: a treated orangy pink CVD stone in GIA’s 2024 review glowed red under deep UV, which GIA put down to a high concentration of NV centres; see do lab-grown diamonds glow under UV?

Do they make lab-grown black diamonds?

Yes. IGI grades them: report LG731580548, dated 10 September 2025, describes a 0.95 ct round lab-grown diamond with the colour grade Fancy Black, grown by CVD, with “Indications of post-growth treatment”. How black lab diamonds get their colour is something we could not verify: none of the GIA research cited on this page explains it. So ask the seller how the colour was made and whether it came after growth, and buy a stone with a report number you can look up. Like the other colours, a black stone gets a fancy colour grade, here Fancy Black, rather than a D-to-Z letter.

How does the grading report show where the colour came from?

Read the comments, not just the colour grade. On the IGI reports above, the comments name the growth method, CVD or HPHT, and say either “As Grown - No indication of post-growth treatment” or “Indications of post-growth treatment”. GIA’s Laboratory-Grown Colored Diamond Report gives a full quality assessment, a plotted clarity diagram and an assessment of growth type and post-growth treatment; a Color Identification version describes the colour and how it is distributed, with the same growth and treatment assessment. Both are for loose stones of 0.15 ct or more, are digital only, and come with “Laboratory-Grown” and the report number laser-inscribed on the girdle. GIA’s Premium and Standard assessment is for colourless and near-colourless lab diamonds only; see IGI vs GIA for lab-grown diamonds. A listing may say nothing about treatment (what US rules require is covered in CVD vs HPHT), so type the report number into the laboratory’s own site yourself: see how to check a diamond report number. To compare prices, line up stones whose reports match on colour grade, carat weight, clarity and treatment, then check today’s price on each listing. The checks on our lab-grown diamonds page apply to a coloured stone too.

Frequently Asked Questions

Is a lab-grown pink diamond real?

Yes. It is diamond, grown by CVD or HPHT. Its pink comes from nitrogen-vacancy centres, which in pink CVD stones GIA says are mainly created by irradiation and annealing after growth. Expect the report to say so: both IGI pink reports cited here note “Indications of post-growth treatment”.

Is a lab-grown yellow diamond treated?

Not necessarily. Nitrogen taken in as the crystal grows turns diamond yellow, so yellow can come straight from growth: the IGI report for a 0.30 ct Fancy Vivid Yellow HPHT stone reads “As Grown - No indication of post-growth treatment”. Check the comments on your own stone’s report.

Are blue lab-grown diamonds coloured by boron?

Some are. GIA says adding boron during growth gives blue crystals, and blue HPHT stones doped with boron were among the first gem-quality lab diamonds. But GIA has graded a few blue CVD stones coloured by irradiation, and the IGI report for a 0.93 ct Fancy Vivid Blue CVD stone notes “Indications of post-growth treatment”, so read the report.

Can you tell a coloured lab diamond from a natural one by eye?

Not reliably. GIA notes that coloured HPHT lab diamonds often show colour zoning in geometric patterns, unlike the zoning occasionally seen in natural diamonds, but CVD stones usually have even colour. A report from a gem laboratory settles it; see can a jeweller tell if a diamond is lab-grown?

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