Diamond Necklace extended her unbeaten record to six races with a dazzling victory at Goodwood, and now the Prix de l'Arc de Triomphe looms on the horizon for the star filly. Her effortless Nassau Stakes success has catapulted her to 10-1 third-favourite for Europe's premier middle-distance contest, sparking intense speculation about her autumn campaign.
Diamond Necklace Dominates the Nassau Stakes
Under a confident ride from Ryan Moore, Diamond Necklace cruised past Friendly Soul inside the final quarter-mile, scoring by two-and-three-quarter lengths. The win marked her fourth Group One triumph and confirmed her status as the leading filly over 10 furlongs in Europe.
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Trainer Aidan O'Brien was full of praise, saying: "Diamond Necklace is a lovely filly who has danced every dance. She has options now, whether she stays at a mile-and-a-quarter and goes to the fillies' race in France, or to Leopardstown or an Arc trial."
Arc de Triomphe Odds and Contenders
With the Arc just months away, bookmakers have installed Diamond Necklace as the 10-1 third-favourite, behind only Daryz, last year's winner, and stablemate Constitution River, who is the 3-1 favourite after winning the French Derby and Eclipse Stakes.

While stamina for the 12-furlong trip remains untested, history is on her side: female runners have won nine of the last 15 runnings of the Arc. O'Brien added, "It is possible. I don't know how far we ask her to go, but the next run will tell us."
Comparing Diamond Necklace's Record
| Race | Distance | Result |
|---|---|---|
| Nassau Stakes (Goodwood) | 10f | Winner by 2.75 lengths |
| Prix de Diane (Chantilly) | 10.5f | Winner by a nose |
| Group One wins (career) | Various | 4 wins |
| Unbeaten streak | — | 6 races |
Key Takeaways for Racing Fans
- Diamond Necklace is unbeaten in six starts, with four Group One victories.
- She is now 10-1 third-favourite for the Prix de l'Arc de Triomphe.
- Trainer Aidan O'Brien has not ruled out an Arc bid, with a decision expected after her next run.
- Female horses have won 9 of the last 15 Arcs, boosting her credentials.
- Constitution River remains the stable's leading Arc hope.
What's Next for Diamond Necklace?
O'Brien indicated that Diamond Necklace could head to Deauville for the Prix Jean Romanet in August or Leopardstown in September as a possible Arc trial. Her connections are keen to test her stamina gradually, and her next outing will be crucial in determining whether she lines up at Longchamp.
With the racing world watching, Diamond Necklace's potential Arc participation adds an intriguing subplot to an already compelling season. Her combination of speed, class, and an unblemished record makes her a fascinating contender.