The 6-1 shot held off Godolphin stablemate Opinion Poll to win by half a length, with Saddler’s Rock in third.
The inquiry was launched after the top two were seen to bump into each other on two occasions near the finish.
Odds-on favourite Fame and Glory, who won the two-and-a-half mile Group One race last year, finished weakly.
Dettori’s decision to ride Colour Vision ahead of Opinion Poll – ridden by Mickael Barzalona instead – came as a surprise, but the grey was vindicated with a thrilling win.
"Whatever happened, they are two very good horses that finished first and second and that's a good thing," Godolphin chief Sheikh Mohammed said afterwards.
"You have to wait a year to prepare your horse to come here and even the second horse ran a great race."
In other races on day three of Ascot, Princess Highway won the Ribblesdale Stakes ahead of The Fugue and Shirocco Star, while Reckless Abandon beat Gale Force Ten and Ian’s Dream in the Norfolk Stakes.