Left: Jeanne Toussaint, 1950's. Center: Countess Mona von Bismarck 1958, photographed by her dear friend Cecil Beaton while wearing her carved emerald and diamond bracelet, emerald and diamond cluster necklace and clip-on earrings from Cartier. Right:&nbsp;Princess Grace Kelly in a 10.47ct Cartier diamond engagement ring, given to her by Prince Rainier, designed by Cartier under Jeanne Toussaint.&nbsp;