The popular phrase diamonds are a girl’s best friend dates back to the song of the same name written for the 1949 Broadway musical Gentleman Prefer Blondes and was later presented and immortalized in the 1953 film version of the show by Marilyn Monroe. Monroe sang of her desire for sparkling square and pear-shaped diamonds along with diamond baguettes from a man who “gives expensive gifts of jewels” from the likes of Tiffany, Cartier, Black Starr and Harry Winston in the legendary song. This summer, diamonds are once again a girl’s best friend with watchmaker Swiss Legend’s five new watch collections…