Gosden sent the five-year-old to France in preference to a clash with stablemate Enable in the Yorkshire Oaks later in the week, and the decision paid dividends.
Having run a series of creditable races in Group Ones in her career, she finally broke her duck at the highest level last time out in the Grand Prix de Saint-Cloud.
With that boosting her confidence, Coronet always looked the likely winner again in a deep field, with Dettori kicking clear over a furlong out as Coronet displayed a sharp turn of foot – despite running over shorter than her ideal distance.
Gosden told Sky Sports Racing: “She’s done it well. It’s a sharp trip for her – she has that weird way of running with her head on an angle, but it doesn’t stop her.
“She’s been a great filly to train. Hopefully she’ll have one more run now in the Filly & Mares at Ascot on Champions Day.
“Breeding is a tough game, but Prince Faisal (owner of Denford Stud) has been doing it for some years. The owner/breeders are passionate about it, and it’s lovely to have a good one for them.”
Dettori said: “She’s a wonderful filly and doesn’t know how to run a bad race.”