Diamond Necklace added another chapter to an extraordinary European Classic campaign for trainer Aidan O’Brien when she dug deep to capture the Prix de Diane Longines at Chantilly on Sunday, overcoming adversity in both the race and the closing stages to secure a hard-fought victory over the fast-finishing Pink Panthera.

The race unfolded at a relentless tempo from the outset. Wayne Lordan sent Moments of Joy forward immediately and established a strong gallop, a tactic that appeared designed to test the field and create ideal conditions for stablemate Diamond Necklace. The pace intensified further when the wide-drawn Esna pressed on from the outside, ensuring there would be no respite through the opening stages.

While the leaders traded blows up front, Pink Panthera endured a difficult beginning. Slow from the gates, the French outsider was forced to play catch-up early as Tony Piccone worked to keep her in touch.

As the field approached the straight, Inis Mor emerged as a major threat. Having enjoyed a perfect stalking trip behind the leaders, she swept through along the rail and briefly looked set to take command of the race.

That advantage proved short-lived. Ryan Moore, aboard Diamond Necklace, angled his mount into clear running in the center of the track, while Pink Panthera launched a sweeping challenge from the rear. In a matter of strides, the pair had surged alongside Inis Mor and taken the race into a two-horse battle.

Pink Panthera appeared to gain the upper hand inside the final furlong, but Diamond Necklace responded when asked. Showing both determination and stamina, she rallied once more and edged ahead in the closing strides to secure victory by a short neck.

The demanding pace contributed to a notably fast performance. Diamond Necklace stopped the clock in 2:03.78, missing the race record set by the outstanding Trêve in 2013 by just one-hundredth of a second.

Although narrowly denied a place in the record books on time, the filly secured a significant achievement of her own. She became only the fifth filly to complete the Marcel Boussac, Poule d’Essai des Pouliches and Prix de Diane treble, joining Allez France, Divine Proportions, Zarkava and Blue Rose Cen.

Bred in Normandy by Écurie des Monceaux, Diamond Necklace was offered through Arqana as a yearling and realized a record €1.7 million.

Another Landmark For O’Brien

The victory provided O’Brien with a second Prix de Diane success following Joan of Arc’s triumph in 2021. It also completed his second Prix du Jockey Club–Prix de Diane double after Constitution River's victory in last week's Qatar Prix du Jockey Club.

Notably, Diamond Necklace is by St Mark’s Basilica, who helped O’Brien achieve the same French Classic double five years earlier when winning the Prix du Jockey Club alongside Joan of Arc’s Prix de Diane success.

The Chantilly victory further strengthened an exceptional spring campaign for the Ballydoyle trainer. Across Ireland, England and France, O’Brien has now collected seven of the season’s ten major spring Classics, including the English and Irish 1,000 Guineas, the Irish 2,000 Guineas, the Epsom Derby, the Poule d’Essai des Pouliches, the Prix du Jockey Club and now the Prix de Diane.

Patience Rewarded

O’Brien revealed that confidence in Diamond Necklace’s ability had never wavered and suggested the filly may have even more to offer as her career progresses.

Reflecting on the performance, he said the filly had always displayed exceptional class and praised Moore’s tactical awareness in a race that became complicated during the running. He also indicated that an Arc trial could be considered later in the season before a potential tilt at the Qatar Prix de l’Arc de Triomphe.

Perhaps the most significant observation from the trainer concerned her stamina. O’Brien noted that while some questioned whether she would stay further, her stride remained long and fluent all the way to the line and she showed little sign of physical exertion after the race.

That assessment could shape future plans. O’Brien explained that the team would remain patient, emphasizing that Diamond Necklace is straightforward to train and does not require an intensive workload. For now, connections intend to allow her development to continue naturally before deciding on her next target.

Moore Impressed By Professionalism

Moore, riding the filly for only the second time, highlighted her temperament as one of her greatest assets.

The champion jockey explained that although he encountered minor interference around the bend and was forced to make his move earlier than intended, he always felt confident in the outcome. He described Diamond Necklace as a filly who possesses class throughout a race, praising her balance, professionalism and ability to respond immediately when asked.

According to Moore, she only does what is required to win, a trait often associated with elite performers.

Breeding Success Years In The Making

The result also carried deep significance for breeder Écurie des Monceaux.

Managing Director Henri Bozo described the victory as an emotional milestone, noting that the operation had previously filled placings in the Prix de Diane but had never managed to win it.

Bozo said the success represented the culmination of many years devoted to developing the family, paying tribute to Lady O’Reilly and others who had played important roles in nurturing the bloodline. He added that the victory rewarded the dedication and perseverance of the entire breeding team.

Official Result

1st – Diamond Necklace (Ryan Moore)
2nd – Pink Panthera (Tony Piccone)
3rd – Inis Mor (Oisin Murphy)

Time: 2:03.78
Margins: Short Neck – 2 lengths – 1 length

For Diamond Necklace, the victory confirmed both her quality and resilience. For O’Brien, it was another reminder that one of the most dominant Classic campaigns in recent memory shows little sign of slowing down.