One billion years old and the rarest colour of them all: A five minute guide to the pink diamond

In October 1926, in a scene reminiscent of the recent Louvre heist, a gargantuan nine-carat pink diamond was stolen from Château de Chantilly, France, by two amateur thieves. Unlike recent events, the diamond was, thankfully, found by a chambermaid called Suzanne Schiltx — in a hollowed-out apple of all places.

Now, a century after the event, the Grande Condé is going on display in France.

The pear-cut stone (left) was mined in India and sold to Louis XIII of France — who later gifted it to Louis II de Bourbon, Prince of Condé, as a reward for his services in the Thirty Years’ War. It remained in the possession of the Condé family until 1892 when the last heir ceded it to the French government on condition that it remained on display at the Château de Chantilly. (Though heavily disputed, according to local folklore the château’s head steward, François Vatel, invented crème Chantilly on the premises.)

When it emerges to dazzle the public in October, the Grande Condé diamond will be accompanied by new-fangled gemological analysis and material chronicling its history. Sam Stirrat, a bespoke jewellery designer specialising in engagement rings and fine jewellery, and the founder of Blackacre, is particularly excited about the reaction it’s sure to garner. ‘The shape of it is rather unusual in that it’s not a modern cut,’ he says. ‘The stone isn’t geometrically perfect and that plays into the new trend for interesting and individual cuts.’ See Taylor Swift’s old mine-cut engagement ring. The eight or ten-carat, elongated diamond was hand cut before modern machinery existed (no two old mine-cut diamonds are identical) and helped to spark a mainstream revival of antique diamond shapes.

Ahead of the blockbuster exhibition, here’s everything you need to know about the romantic-hued stone with rising investment value:

1. Pink diamonds are eye-wateringly expensive because of their scarcity — they are among the rarest natural gems on Earth and account for less than 0.01% of total global diamond production. In November 2020, Australia’s Argyle Mine, one of the world’s best sources for pink and brown diamonds, closed. During the 37 years that it was operational, it produced more than 865 million carats of rough diamonds — though the majority of pink ones discovered were under a single carat each. The CTF Pink Star, Williamson Pink Star and Graff Pink are the three most expensive pink diamonds to sell at auction to date. They went for $71.2 million, $57.5 million and $46 million respectively

2. Quite how pink diamonds form is still disputed by gemologists, but it isn’t like most other coloured diamonds, which get their colours from trace elements. Some think they owe their hue to plastic deformation, a geological process of extreme heat and pressure that permanently shifts a diamond’s carbon crystal lattice (a 3D network of carbon atoms) without breaking it. It’s most likely that this natural phenomenon took place as the diamond was forming, probably one to three billion years ago, meaning it may predate the first multicellular life on Earth by more than a billion years
3. The stones are assessed according to their hue, tone and saturation. The latter refers to the intensity of colour which can be faint pink, very light pink, light pink, fancy light pink, fancy pink, fancy intense pink, fancy vivid pink or fancy deep pink. The more vividly intense the stone, the rarer and more expensive it is. ‘One of things that I love is the variation in hues,’ says Sophia Hirsh, the second-generation owner of family-run Hirsh London. Her father, Anthony, was one of the first jewellers in the UK to work with pink diamonds in the mid 1980s and the family have amassed an enviable collection of the pretty stones over the past 50 years. ‘Even if you have two stones that GA [Gemmological Association] certificates as the same, they actually don’t look anything alike. There’s a huge variety even in the same colour category. I love putting together pink diamonds and trying to match them up’

4. The large, natural pink diamonds that command huge prices at auction (think between $10,000 and $1 million per carat) are extremely popular with and fiercely coveted by gem collectors. However that doesn’t mean every-day wearers should feel like they’ve been left out in the pink-less cold. The key, Stirrat says, is to incorporate the smaller and more easily attainable stones into what will surely become your favourite and most-worn pieces. He fondly remembers making a pair of diamond stud earrings for a client, with a series of pink diamonds set into the side profile. His favourite commission, though, was for what Blackare calls the ‘Goa ring’, an asymmetric composition of natural white and rare pink Argyle diamonds. Stirrat designed the gentle twist through the shank to echo the flowing curves of a river — a subtle reference to his client’s Pisces star sign. Hirsh, who revels in pairing blue and pink diamonds together, counts a remarkable dragonfly brooch among her top designs. The intricately engineered treasure was crowned with a central kite-cut pink diamond and had ergonomic wings studded with more pink diamonds. ‘It’s a piece I one day want to see in a museum,’ she says
5. Historic pink diamonds often belonged to royalty or members of the aristocracy. Famous examples include the Darya-i-Noor in Iran’s Crown Jewels and the Williamson Pink Diamond, presented to Elizabeth II as a wedding gift in 1947. And the Grande Condé wasn’t the only pink diamond to weave its way into the hands of French nobility. The Hortensia, a 20-carat, peachy-pink diamond was purchased by Louis XIV of France in 1643 and stolen and recovered twice: first during the unrest of the French Revolution, and second, in 1830, from the Ministry of the Navy. As part of the surviving French Crown Jewels, it is on display in the Apollo Gallery in the Louvre. Marie Antoinette’s own fancy purple-pink, kite brilliant-cut pink diamond ring sold for $13,980,000 at auction in 2025, against an estimate of $7 million

'The Pink Diamond' at Musée Condé in the Château de Chantilly, in partnership with L’ÉCOLE, School of Jewelry Arts, supported by Van Cleef & Arpels, is open October 17, 2026, until January 3, 2027.