La Cote des Montres: The Greubel Forsey GMT Quadruple Tourbillon watch - Titanium and blue
Greubel Forsey - GMT Quadruple Tourbillon in Titanium | Time and Watches | The watch blog
Titanium and blue for the Greubel Forsley GMT Quadruple Tourbillon – FHH Journal
GMT A white gold 24-second inclined tourbillon world time and dual time wristwatch with power reserve indication and three dimensional globe, Circa 2015 | Important Watches | | Sotheby's