By Ewan Gleadow A man on holiday in the United States has returned home with a whopping 7.46-carat diamond after striking lucky. Julien Navas, from France, visited the Crater of Diamonds State Park in Arkansas and found the gem after just a few hours of digging. He said: “I got to the park around nine o’clock and started to dig. That is back-breaking work so by the afternoon I was mainly looking on top of the ground for anything that stood out.” Assistant Park Superintendent Waymon Cox confirmed that Julien had stumbled upon the diamond, which was the size of a gumdrop. The brown-coloured find…