Diamond Necklace stays unbeaten with hard-fought Prix de Diane win

Diamond Necklace did not get the soft Classic procession her French Guineas win hinted at, and that was what made this one matter. At Chantilly on Sunday, the Aidan O’Brien filly had to work through traffic, find a lane and fight all the way to the line to stay unbeaten in the Prix de Diane, holding off Pink Panthera by a neck and showing the sort of toughness that turns a promising runner into a possible leader of her division.

The 2,100-metre race, run since 1843 for three-year-old fillies and worth €1 million, asked a different question from the mile at ParisLongchamp. Ryan Moore kept Diamond Necklace in midfield until the race unfolded, then asked her to close down Pink Panthera, trained by Patrice Cottier, with Inis Mor, from the David Menuisier stable, finishing third. The official time was 2:03.78 over 10.5 furlongs on good-to-firm ground, and more than 21,000 spectators watched the finish.

What stood out was the way Diamond Necklace handled pressure. She had won the Poule d’Essai des Pouliches by three lengths, but this was a tighter, more searching test, and she answered it without losing her shape. She travelled well, stayed composed when the race became messy, and still had enough turn of foot to repel a filly that briefly looked a serious danger in the final furlong.

O’Brien had gone into the race confident the extra ground would suit after her French Guineas success, saying she had come out of that effort well, looked straightforward and well balanced, and reminded him of her sire, St Mark’s Basilica. She proved that belief right in the last stride, and the win gave Moore his first Prix de Diane and O’Brien his second, after Joan Of Arc in 2021.

The result also pushed Diamond Necklace into rare company. She became only the fifth filly to complete the Prix Marcel Boussac, Poule d’Essai des Pouliches and Prix de Diane treble, joining Allez France, Divine Proportions, Zarkava and Blue Rose Cen. With her market cuts for the Irish Oaks, the Eclipse and the Arc, the conversation around her has shifted fast: she no longer looks like just another Ballydoyle Classic winner, but like a filly whose unbeaten record now points toward the biggest summer targets in Europe.