horon has a unique place in the always discreet diamond industry. Established in 1985 in Antwerp by Rajesh Gandhi, the group is present across the value chain, from the sourcing, assortment and sale of rough diamonds to the manufacturing and sale of polished diamonds. Choron Group, which in 2025 acquired AMC, has developed relationships with major mining companies and supplies diamonds to the leading jewellery houses and professionals in the sector.
Some of the most extraordinary stones ever found have passed through its hands, including a 108.39-carat pink diamond discovered at the Kao Mine in Lesotho in 2023. Cut and polished by Choron, this remarkable rough yielded seven stones that range in colour from Fancy Intense Purplish Pink to Faint Pink.
Sales & Sustainability Director at AMC, Julie Maldonado follows these stones from the rough to their new life as cut and polished diamonds. Speaking from the AMC Choron Group booth at GemGenève last May, she explained why coloured diamonds are so rare, the importance of cut and why, compared with white diamonds, the market for these stones is shaped by different factors.
Europa Star Jewellery: Coloured diamonds are the exception. Do some mines produce more than others?
Julie Maldonado: Yes, there are mines that produce more coloured diamonds than others. Ekati in Canada, which is operated by Burgundy Diamond Mines, supplies very distinctive yellow diamonds, in particular those recovered from the Misery Pipe. It’s one of the last Canadian mines in operation. [At the time of the interview, Ekati was facing serious financial difficulty and has since entered receivership]. In southern Sierra Leone, the Zimmi region is known for yellow diamonds with a particularly intense and saturated colour. Some are Type Ib, a rare category of natural diamond. It’s this combination of provenance, colour and specific characteristics that sets Zimmi diamonds apart. In South Africa, Petra Diamonds operates the world-famous Cullinan Mine, which produces some of the rarest, most sought-after blue diamonds. Several legendary blue diamonds originated there, including the Oppenheimer Blue, the De Beers Blue and the Infinite Blue. Other regions of Southern Africa are a source of pink diamonds, especially Angola, Tanzania, Lesotho and South Africa, although in significantly smaller volumes than white diamonds.
Why are certain colours such as red and green so rare?
Mother Nature! Red diamonds and green diamonds are among the rarest of all. Red is caused by distortions in the crystal lattice while green results from exposure to natural radiation under precise geological conditions. Only an infinitely tiny proportion of natural diamonds display these colours, and are therefore much harder to find. Of all coloured diamonds, yellow are the most widespread in nature.
A large proportion of the world’s pink diamonds came from the Argyle Mine. What impact did its closure have on prices?
Argyle’s closure created a premium for diamonds sourced there, which have become collector’s items. Since Argyle ceased operations, the most saturated pinks have become even scarcer, although not all pink diamonds have followed the same trajectory. Their value remains primarily driven by colour, cut, characteristics and provenance.
Is it still possible to detect a diamond whose colour results from treatments such as high temperature, high pressure or irradiation?
Yes. Gemmological laboratories use advanced testing to detect known treatments and determine whether a diamond’s colour is natural or has been artificially modified. A report issued by the GIA or another reputable laboratory is essential for large stones. At the rough stage, we also analyse each diamond carefully before cutting, but for a different purpose: to understand its colour distribution and determine which cut will best reveal and enhance its natural colour.
What is Choron Group’s area of expertise?
Choron Group is recognised for its expertise in rough diamonds, for its strong relationships with mining companies and for the quality of its relationships within the broader diamond ecosystem. We have a fabulous inventory of Fancy Vivid Yellow diamonds, including a number of emerald-cut, which is an unusual combination. Not every stone is flawless and optimising colour with an emerald cut presents a particular challenge. This is precisely where our expertise lies. We work with some of the finest cutters and are renowned for our ability to maximise a diamond’s colour and for the quality of our cuts. Cut changes everything. It brings out colour and makes the difference between a beautiful stone and, as we say in our professional jargon, an “ugly stone”. Once a stone has been cut, first we grade it ourselves then we send it to the GIA, which is the foremost authority in diamond grading. The GIA’s independent analysis provides confirmation of the stone’s individual characteristics. Colour grading is a decisive factor in the value of a stone. Moving up or down a colour grade can represent a difference of several thousand dollars and considerably more for important stones.
Compared to white diamonds, is cutting a coloured diamond a more complex process?
Yes. More complex and often more time-intensive, in some cases up to several months. There is no margin for error when cutting a large rough diamond. It demands an enormous amount of preparation, planning and precision. But when you’re lucky enough to follow a stone across its entire journey from the rough all the way to the final cut and polished diamond, it’s an incredible experience.
In 2023 a 108.39-carat Type IIa Fancy Intense Pink diamond, one of the largest ever found, was discovered at the Kao Mine in Lesotho. Cut and polished by Choron Group, it yielded the KAO Legend Collection: a suite of stones from Fancy Intense Purplish Pink to Faint Pink.
Where do you begin with such an exceptional rough?
Possibly the most incredible thing about this rough is that it yielded seven stones displaying different shades and intensities of pink. We set out to maximise its potential, thanks to precise analysis of its structure and colour distribution. Our specialists have the expertise to assess a rough diamond and predict what it could reveal once cut and polished. With a stone of this importance, every single decision can influence the colour, shape, carat weight and, ultimately, the end result.
What happened to these seven stones?
Some have been sold and found new homes around the world. We would have loved to keep the collection together, because they are all part of the same story, but their individual value made this almost impossible. In the end, the suite was split up.
Why would you say coloured diamonds are holding their value, compared with white diamonds?
Firstly, I would say it’s a question of scarcity. Fancy colour diamonds are exceptionally rare, less accessible and appeal to a very specific clientele. Character is another factor. There is something genuinely remarkable and unique about each coloured diamond. I think there is also a patrimonial aspect that helps maintain value over time. The markets for coloured and white diamonds function in different ways. Whereas there is a reference price for white diamonds, such as the Rapaport list, the value of fancy colour diamonds is individually based on the most recent transactions, auction sales and each stone’s characteristics. This is how the market is built.
Certain categories of fancy colour diamond have seen a significant appreciation over the long term, although performance varies considerably based on colour, intensity, cut, characteristics and provenance.
Who buys coloured diamonds? Investors or collectors?
Both, although we also see strong interest from jewellery houses looking for exceptional stones for specific creations. One of the fascinating things about coloured diamonds is that the same stone might capture the attention of a house for a particular project, but can equally appeal to a collector seeking a rare and distinctive stone.
Why do you think so few diamantaires specialise in coloured diamonds?
Because you don’t become a specialist overnight. You must have the relevant knowledge and a clientele that understands these stones, too. Also, given the values involved, you need a solid financial structure. The banks we work with are genuine partners: these stones require significant investments and the ability to tie up capital. I believe it’s always better to remain within your area of expertise rather than try to be a jack of all trades. Some specialist diamantaires have even developed their own coloured diamond training programmes. The Fancy Color Research Foundation, FCRF, provides valuable market data and research. We actually partnered with the FCRF and the Natural Diamond Council to co-author a report on fancy colour diamonds, bringing together market insight and industry expertise.
Which colours are most in demand this year?
Pinks remain particularly sought-after, especially highly saturated stones such as Fancy Vivids. Blues still have a strong following, as do certain yellows, which are more accessible and have a broader market.
Ultimately, though, customers are looking for a stone that really stands apart. One with strong colour, beautiful saturation and an interesting cut. And when there is significant provenance, this adds another dimension to the story. With coloured diamonds, it’s never about colour alone. It is the combination of all these elements that make a stone truly rare and desirable.
Over the past two to three years, there has been a surge in interest, among end customers, in colours that previously they might not have considered, such as pinkish-brown, fancy brown or orange-brown. Why do you think that is?
I think it comes down to a combination of factors. Even though the trend began before De Beers launched its Desert Diamonds, the campaign certainly helped build momentum and bring these colours to a wider audience. Celebrities have also influenced demand: think of the conversation around a certain engagement ring or another piece of jewellery featuring brown-toned stones.
Our perception of diamonds has also evolved. It used to be all about finding the whitest, most flawless stone. Today, customers are increasingly drawn to colour and character.
This could reflect the way people are wearing diamonds today. More women are wearing diamonds outside the traditional context of an engagement ring. Men are increasingly open to wearing jewellery, too. That’s one possible explanation, although as a diamantaire, we don’t always know who the final customer will be.
Price may have played a role, too. Brown diamonds used to be relatively inexpensive and certain buyers spotted an opportunity, recognising that they were at a very different price point compared with other coloured diamonds. Now, certain categories of brown diamond have increased substantially in value and I often hear colleagues saying they regret not having bought them years ago.
Is there one coloured diamond that stands out in your mind more than any other?
I’ve been lucky enough to see diamonds in every colour, but there is one in particular that made a lasting impression. Suffice to say it’s the kind of diamond you never forget. The colour was exceptional, its presence extraordinary. There was that indescribable sensation of holding something rare and special in your hand. I actually had goosebumps the first time I saw it. That instinctive feeling of being in the presence of a truly exceptional stone.
