Trainer Aidan O’Brien talks about his fillies Diamond Necklace and Moments of Joy

On Tuesday, France Galop launched its series of press conferences dedicated to the 2026 edition of the Prix de Diane Longines (Group 1, the highest level of international racing). The prestigious Classic, one of the highlights of the global Flat racing calendar and first run in 1843, will take place on Sunday, June 14, 2026, at Chantilly Racecourse.

Run over 2,100 metres, this prestigious contest is restricted to three-year-old fillies and offers total prize money of €1 million.

This first media gathering provided an opportunity to highlight the Irish-trained contenders from the yard of Aidan O’Brien.

About Diamond Necklace

“We'll probably run two fillies, Diamond Necklace and one of the others. It could be Moments Of Joy, we're thinking of running.

With Diamond Necklace, since she won the French Guineas, everything has went well. I've been very happy with her. The plan was always, if everything went well in the Guineas, to come back here. Everything has been very good since her last victory. I think she’s even better on better ground.

Obviously, she won nicely the last time and it's her second run of the year. We were delighted. So if she did that again, obviously, we'd be over the moon. But everything has went well and we've been very happy with her since. And we always thought a mile and a quarter shouldn't be a problem to her.

Obviously, we're going to learn more on Sunday. And you're never sure what to do, but we always thought this distance wouldn't be any problem. She's good, very straightforward. She's well balanced. She's a medium-sized filly and usually travels well in her races.

She's very like her sire St. Mark's Basilica. When he went up to a mile and a quarter, he improved again and everything she does is very like him, really. 

Obviously, the Diane is a very prestigious race, very important for a filly and, obviously, at Chantilly. And it is a Classic. Obviously, it's a tough race to win.

So you need a very good filly to do it, really, we always think.”

But are tactics important in this race?

“I don't think so, it's always straightforward and I think it suits everybody when there's an even pace. I don't think it's ever about tactics. All we ever want is an evenly run race and then everybody finds out where they stand afterwards and whether their horse gets the trip or doesn't get the trip.

And when the pace is like that, obviously, people and horses aren't on top of each other, really. That's the only reason ever. And I think everybody kind of knows where they stand when there's an evenly run race.”

Will she stay 12f at some point?

“It's possible. You obviously couldn't be sure until you do it, but it definitely is possible, especially being by St. Mark's and on her dam side as well, obviously.”

About Moments Of Joy

“She ran in the Musidora the last time, the Oaks trial at York. It went a little bit steady for her, but she ran okay. So obviously she was a possible for the Oaks.

She had a couple of choices: the Epsom Oaks, Ascot for the Ribblesdale and Chantilly. So we're thinking at the moment she might go to the Diane. We think there's more improvement to come from her, and we think she'd like the trip, and we think she'd like the track as well.

I think she'd like light and nice ground. I don't think she'd be mad about soft ground. She's a very good mover. »

You go out on your own onto the track, and you actually walk the track with your jockeys, and what is it people have been asking? What is it you look for? What is it you look at when you do that?

« We go through every furlong, obviously, as much as we do. We go on the grass on the track and try to prepare as well as we can, really, for all different kinds of scenarios. And we speak and talk and communicate a lot as we go along. And we see where the best ground is.

I think it's everything, really. It's talk and walk and just prepare as well as we can, really.”

Aidan O’Brien Looking to Return to Winning Ways

The son of Irish farmers, Aidan O’Brien set up as a trainer at the age of 23. He saddled his first runner on June 7, 1993—and the horse won. He quickly established himself as a dominant force in Irish National Hunt racing, winning the Champion Trainer title on several occasions.

In 1996, John Magnier approached him to succeed Vincent O’Brien—his namesake, though not a relative—at Ballydoyle, the largest private training centre in Europe, located in Ireland. He thus became the trainer for Coolmore, the international powerhouse with operations in Ireland, the United States and Australia, a true production line for champions and future stallions.

Aidan O’Brien has recorded nearly 450 Group 1 victories on the Flat across nine countries, four continents and both hemispheres. As he embarks on his 34th season, he has been crowned Ireland’s Champion Flat Trainer on 28 occasions.

He has won the Prix de Diane Longines once, in 2021 with Joan of Arc. She was a daughter of the broodmare You'resothrilling, whose remarkable record includes four runners in the Diane—an exceptional achievement: Happily, fourth in 2018 over a trip that stretched her stamina; Coolmore, fifth in 2016; Joan of Arc, the winner in 2021; and Toy, twelfth in 2022.

Aidan O’Brien’s Runners in the Prix de Diane

Italics indicate fillies placed in the first three.
Bold indicates winning fillies.