Coloured Lab-Grown Diamonds Explained: Production, IGI Certificates and Pink Diamond Guide (2026)
This is an easy guide written specifically from the buyer's point of view. Rather than explaining the lab science, it tells you everything a buyer should know before choosing a coloured lab-grown diamond: how it is made, how to read the certificate, which colours are worth buying, and how to choose a pink diamond, the most popular colour in Asia.
Buyer's view · Key points first
A coloured lab-grown diamond is a real diamond, and its colour usually comes from a permanent post-growth treatment. The most common and most affordable colour is yellow; the most popular in Asia is pink. When choosing a pink diamond, remember three things: choose only Fancy Intense or Fancy Vivid Pink; prefer a round or cushion shape; and if photos don't show the colour clearly, always ask for a video. New to lab-grown diamonds? Start with our complete guide to lab-grown diamonds.
What Is a Coloured Lab-Grown Diamond?
A coloured lab-grown diamond is a real diamond grown in a laboratory that shows a distinct colour. Like a colourless lab-grown diamond, it is made of carbon and has a hardness of 10. The difference is a set of tiny structures inside the crystal that absorb certain colours of light, so the diamond appears yellow, pink, blue or green.
Diamond colour comes from one of two sources:
Colour formed during growth
Trace elements enter the crystal while it grows: nitrogen makes a diamond yellow, boron makes it blue. Certificates usually describe this as "As Grown".
Colour added after growth
The diamond is grown first, then its inner structure is changed by physical processes such as high pressure and high temperature, irradiation or annealing. Most pink, red and purple lab-grown diamonds on the market are made this way.
"Colour treatment" may sound like dyeing, but it is completely different. There is no dye and no surface coating. The change happens at the atomic level inside the diamond, so the colour runs through the whole stone and cannot wash or wear off.
How Are Coloured Lab-Grown Diamonds Made? Rough, Colour and Cutting in 3 Steps
From a buyer's point of view, there are only three steps to remember: grow the rough crystal, add the colour, then cut and polish it into the diamond you see.
Grow the rough
A CVD (chemical vapour deposition) rough looks like a flat rectangular block, built up layer by layer as carbon atoms settle on a seed plate. Freshly grown rough usually has a brown or grey tint.
How much trace nitrogen the rough contains decides which colours it can later become, so choosing the right rough is the first step.
Add the colour
A typical pink process: high pressure, high temperature treatment first removes the brown tint, then electron-beam irradiation, then annealing in a high-temperature furnace. The crystal develops structures that absorb green and yellow light, and the diamond turns pink.
Each colour uses a different process; see the table in the next section.
Cut and polish
The cutter chooses the cut based on the rough's shape and colour distribution. For a coloured diamond, the cut affects not only sparkle but also how even the colour looks and whether dark areas appear. That is why shape matters so much for pink diamonds.
In its journal Gems & Gemology, GIA has documented pink CVD lab-grown diamonds that went through multiple treatments: high pressure, high temperature processing, then irradiation, then low-temperature annealing, forming nitrogen-vacancy centres that create the pink colour (GIA lab note).
Coloured Lab-Grown Diamond Processes: Pink, Yellow, Blue and Green Compared
Each colour starts from a different type of rough and uses a different process. You don't need to memorise the terms; just remember that different colours need different numbers of steps, and more steps usually mean a higher cost.
| Colour | Typical rough | Typical process | In simple terms |
|---|---|---|---|
| Yellow / orange-yellow | Nitrogen-rich HPHT rough | Coloured during growth, sometimes with extra HPHT treatment | Nitrogen absorbs blue light so the stone looks yellow; fewest steps |
| Pink / red / purplish pink | Mainly CVD rough with trace nitrogen | HPHT to remove brown → irradiation → annealing | Structures form that absorb green and yellow light; most steps |
| Green / blue-green | High-purity or trace-nitrogen rough | Irradiation | Irradiation creates structures that absorb red and orange light |
| Blue | Boron added during growth, or high-purity rough | As Grown, or irradiation | Boron absorbs red light so the stone looks blue |
GIA's reference chart on lab-grown diamonds also notes that the colour of HPHT and CVD diamonds depends on growth conditions and post-growth treatments, and that fancy colours can be either as grown or treated (GIA: Features of Synthetic Diamonds).
The Coloured Lab-Grown Diamond Market: Why Yellow Is the Most Common and Cheapest
Look at coloured diamonds on the market and you will notice that yellow is the most plentiful and the cheapest. The reasons are simple:
First to be mass-produced
Yellow was the first colour that could be produced in large quantities. During HPHT growth, nitrogen easily enters the crystal and the diamond naturally turns yellow.
HPHT, fewer steps
Yellow diamonds are mainly made from HPHT rough and are often already coloured when growth finishes, so they need few extra steps.
Other colours mostly CVD
Pink, red and purple are mainly made from CVD rough through several treatments, with higher cost and lower yield, so they cost noticeably more than yellow.
Where Asia is different: yellow may be the most common, but in Hong Kong, Japan and Taiwan, pink is the best-selling coloured diamond. Its soft colour suits white gold and rose gold, and it works for engagement rings and everyday wear. That is why the second half of this guide focuses on choosing pink.
How to Read a Coloured Lab-Grown Diamond Certificate: IGI Colour Grades and Treatment
Colourless diamonds are graded with the letters D–Z. Coloured diamonds are graded completely differently, by how strong the colour is. GIA describes coloured diamonds by hue (which colour), tone (how light or dark) and saturation (how strong), then uses terms such as Fancy Light, Fancy Intense and Fancy Vivid (GIA: coloured diamond reports). IGI uses the same Fancy grade terms.
When you receive an IGI report for a coloured lab-grown diamond, check it in this order:
- "Laboratory Grown": confirms it is a lab-grown diamond report; the girdle also carries a laser inscription.
- Colour grade: for example "Fancy Intense Pink" or "Fancy Vivid Pink". Watch for any modifying colour in front, such as Brownish or Grayish, which directly affects how the stone looks.
- Growth method: the report states CVD or HPHT.
- Comments: a diamond coloured after growth will say "Indications of post-growth treatment" alongside the growth method; untreated colour is described as As Grown.
- Verify online: enter the report number on the IGI website.
A note from MIHO (IGI-certified diamond specialist): don't be put off by the word "treated". Almost every pink lab-grown diamond on the market is colour-treated; it is standard industry practice. What matters is that the certificate states it clearly and honestly, and that the colour grade itself is good enough. For the difference between the two labs, see IGI vs GIA certification.
Will a Coloured Lab-Grown Diamond Fade? Colour Stability and Care
No. The treatment changes the diamond's atomic structure, and the treatment itself takes place at temperatures from several hundred to over two thousand degrees Celsius, far above anything in daily life. Everyday wear, sunlight, washing your hands and ultrasonic cleaning will not change the colour.
The one thing to watch: if you later resize or repair the ring, ask the jeweller not to heat the coloured diamond directly with a torch. An open flame at very high temperature can affect the colour structure. The usual practice is to remove the stone first and reset it after the repair.
For more on diamond treatments in general, see GIA: diamond treatments.
Pink Diamond Guide: Why Pink Lab-Grown Diamonds Are Asia's Favourite
Natural pink diamonds are extremely rare, often costing hundreds of thousands to millions of dollars. Lab-grown pink makes the same soft colour affordable, and with Asian taste favouring gentle, romantic colours, pink has become the region's most popular coloured diamond.
Pink is also the coloured diamond buyers most often get wrong. Two stones both called "pink" can look very different. It comes down to three things: grey tone, colour grade and shape.
The Grey Tone Problem: The Most Common Pink Lab-Grown Diamond Trap
Because pink lab-grown diamonds go through several treatments, some pick up a grey or brown undertone that makes them look as if they are behind a haze. The lighter the colour, the more visible the grey, because the pink is not strong enough to cover it.
"When we buy pink diamonds, the first thing we look at isn't the certificate; it's whether the colour is clean. Put two stones side by side that both say Fancy Intense Pink on the report, and one can be clear while the other looks hazy. It happens all the time. Grey tone doesn't always show on the certificate, so the only way is to compare stone by stone by eye. We would rather reject a stone than let a customer end up with a dull pink."
— Winston Wu, MadisonDia diamond buyer, IGI-certifiedGreyish pink diamonds share three traits:
Hard to see in photos
Strong lighting, white backgrounds and editing can hide the grey; buyers only notice when the stone arrives.
Most common in lighter grades
In lighter grades such as Fancy Light and Fancy, the pink isn't strong enough to cover the grey.
Made worse by some shapes
Pear, oval and marquise shapes have a bowtie dark area, and grey tone makes it darker. See the shape section below.
Which Pink Diamond Colour Grade to Choose? Only Fancy Intense or Fancy Vivid Pink
Pink colour grades run roughly from light to strong as shown below. Our advice is simple: choose only Fancy Intense or Fancy Vivid Pink; we don't recommend any other grade.
"A pink diamond's value lies in the pink itself. Many customers are first drawn to the low price of Fancy Light, then find the colour so pale it barely reads as pink, and greyish too. If the colour isn't strong enough, there's no point in choosing pink. Better to put the budget towards a Fancy Intense or Vivid that genuinely looks beautiful."
— MIHO, IGI-certified diamond specialistOn clarity, the pink colour itself hides fine inclusions, so VS1 is already eye-clean. MadisonDia offers pink diamonds in VS1 and VVS2 at the same price, and we offer VVS2 first when the colour is equal. But colour always leads: a clean-pink VS1 will always look better than a greyish VVS2.
Go deeper: for real videos comparing Fancy Intense and Fancy Vivid, why stones within one grade still differ, and how to spot a greyish pink, read Fancy Intense vs Fancy Vivid Pink: colour grades and the grey tone problem, compared on video.
Which Pink Diamond Shape to Choose? Round and Cushion, Without the Bowtie
For pink diamonds, we always recommend cushion or round first. With these two shapes, buyers can stop worrying about one thing in particular: the bowtie effect.
Round and cushion
Symmetrical facets return light from every direction, so the pink looks even and full, with no bowtie.
A cushion's large facets hold the pink especially well, so the colour looks deeper; a round gives the most sparkle and suits any setting.
Pear, oval and marquise
These fancy shapes have a bowtie effect: a dark band across the centre.
Pink diamonds already risk a grey tone, and grey makes the bowtie darker and deeper, affecting the whole stone. Unless you have seen a video and are sure you like it, we don't recommend them as a first choice.
"On a colourless oval or pear, a light bowtie actually adds contrast. On a pink diamond it's different. Pink tends to carry a grey tone, so the bowtie becomes a grey-black patch, and from a distance the pink looks cut in half. When customers ask me which shape to choose for pink, my answer is almost always cushion or round, so they never have to think about the bowtie."
— MIHO, IGI-certified diamond specialistDo you need a Hearts & Arrows pink diamond? No. Hearts & Arrows is all about frequent, bright white flashes, which is a plus for a colourless diamond. On a pink diamond, all that white light dilutes the pink and weakens its colour character. That is why pinks are rarely cut as Hearts & Arrows, and it isn't worth paying extra for. With pink, what matters is colour strength and whether there is any grey, not the symmetry pattern.
For a full illustrated explanation of the bowtie effect, see How to choose an oval lab-grown diamond: ratio and bowtie explained.
Can't See the Pink Clearly in Photos? Always Ask for a Real Video Before Buying
A coloured diamond's cut and colour are far more sensitive than a colourless stone's. The same pink diamond can look like two different stones under different lighting, backgrounds and angles. So our advice to every buyer is:
If the photos don't show the colour very clearly, always ask for a video. A video shows how the colour changes as the stone moves, whether there is any grey and whether dark areas appear, none of which a single photo can tell you.
When you watch the video, look for:
- Natural or white light: avoid warm yellow lamps or strong jewellery spotlights, which make pink look stronger than it is.
- A colourless diamond beside it: the easiest way to see whether the pink is clean or greyish or brownish.
- The stone in motion: check that the colour stays even and no dark area appears in the centre.
- Match against the certificate: make sure the stone in the video matches the Fancy grade on the report.
At MadisonDia, customers can ask for a real video of the diamond before any purchase. We also specialise in pink diamonds: we pick out the best pink stones for you first, then you choose from them, so you don't have to compare a large number of stones yourself.
MadisonDia Pink Lab-Grown Diamonds vs the General Market
Large online platforms offer a wide choice of shapes and colour grades, which suits buyers who already know exactly what they want. MadisonDia filters first on the buyer's behalf:
| Item | MadisonDia | Common in the market |
|---|---|---|
| Colour grade | Fancy Intense or Fancy Vivid Pink only | Fancy Light to Vivid; buyer must judge |
| Grey screening | Greyish and brownish stones rejected by our buyer first | Certificate may not show grey; buyer must judge |
| Clarity / cut | VS1–VVS2, Ideal / EX / EX | Anything from SI to VVS |
| Certificate | Every stone has an IGI report | IGI, GIA or other labs, depending on the seller |
| Shape advice | Mainly round; round and cushion recommended | All shapes mixed |
| Video check | Real video available before any purchase | Some sellers show only computer renders |
Pink Lab-Grown Diamond Prices (USD, November 2026)
Below are MadisonDia loose pink lab-grown diamond prices: round brilliant, Fancy Intense or Fancy Vivid Pink (same price for both), VS1–VVS2 clarity, Ideal / EX / EX cut, each with an IGI report. Current prices are shown on the loose pink lab-grown diamond collection.
A pink diamond costs roughly twice as much as a colourless lab-grown diamond of the same size, mainly reflecting the treatment steps and the cost of selection. To set a pink diamond in a ring, browse our pink diamond rings, or compare colourless loose lab-grown diamonds.
Want to see the pink diamonds we would pick for you?
Tell us your budget and the shade of pink you like. We will pick out the best few stones and send real videos to compare. Wherever you are, you can see every diamond's colour clearly before you pay.
Coloured Lab-Grown Diamond and Pink Diamond FAQ
Is a coloured lab-grown diamond a real diamond?
Yes. Like colourless lab-grown and natural diamonds, it is made of carbon and has a hardness of 10. Tiny structures inside the crystal absorb part of the light, so it appears yellow, pink, blue or green. Every stone can be certified by an international lab such as IGI.
How is the colour created, and will it fade?
Colour comes from two sources: trace elements that enter the crystal during growth (As Grown), such as nitrogen for yellow and boron for blue; or physical processes after growth, such as high pressure and high temperature, irradiation or annealing, that change the inner structure. It is not a dye or coating; the colour runs through the whole stone and will not fade with daily wear. The only caution is not to heat the diamond directly with a torch during repairs.
Why are yellow lab-grown diamonds cheaper than pink?
Yellow was the first colour that could be mass-produced. Yellow diamonds are mainly made from HPHT rough, where nitrogen easily enters the crystal during growth and turns it yellow, so very few steps are needed. Pink is mainly made from CVD rough through several steps: HPHT to remove brown, irradiation and annealing. The higher cost makes pink noticeably more expensive.
Does the IGI certificate say a coloured diamond is treated?
Yes. An IGI lab-grown diamond report states Laboratory Grown and the growth method (CVD or HPHT). A diamond coloured after growth will say "Indications of post-growth treatment" in the comments; untreated colour is described as As Grown. Almost every pink lab-grown diamond is colour-treated; it is standard industry practice.
What is a greyish pink diamond?
Some pink lab-grown diamonds have a grey or brown undertone that makes them look hazy and dull. The lighter the colour grade, the more visible the grey, and strong lighting or editing can hide it in photos. Choose a stronger colour grade and ask for a real video.
Which pink diamond colour grade should I choose?
Only Fancy Intense Pink or Fancy Vivid Pink. Fancy Intense is a soft pink, ideal for everyday wear; Fancy Vivid is the most saturated, with pink you see at a glance. Lighter grades such as Fancy Light and Fancy lack colour and tend to look greyish, so we don't recommend them.
What is the best shape for a pink diamond?
Cushion or round. Their symmetrical facets make the pink look even and full, with no bowtie effect. Pear, oval and marquise have a bowtie dark area, and a pink diamond's grey tone makes it darker, so unless you have seen a video and are sure you like it, we don't recommend them as a first choice.
Should I choose a Hearts & Arrows pink diamond?
No need. Hearts & Arrows is about frequent, bright white flashes, which helps a colourless diamond, but on a pink diamond the extra white light dilutes the pink and weakens its colour. Pinks are rarely cut as Hearts & Arrows and it isn't worth paying extra for. Focus on whether the grade is Fancy Intense or Fancy Vivid Pink and whether the pink is clean, without grey.
Why should I watch a video before buying a pink diamond?
The same pink diamond can look very different under different lighting, backgrounds and angles, and photos are easy to edit. A video shows whether the colour stays even as the stone moves and whether there is any grey or dark area. At MadisonDia you can ask for a real video before any purchase, and we pick out the best pink stones for you first, then you choose.
How much does a pink lab-grown diamond cost?
MadisonDia loose pink lab-grown diamonds are round brilliant, Fancy Intense or Fancy Vivid Pink, VS1–VVS2 clarity, Ideal / EX / EX cut, with an IGI report: 1 ct from $519, 1.5 ct from $795 and 2 ct from $1,104, with the same price for both colours. Current prices are shown on the website.