gold and platinum ring with diamonds

An 18 carat white gold and platinum ring with a navette-shaped element with three old cut diamonds set in the length (0.7 and two times 0.6 carat) with a border of old cut diamonds alternated with single cut diamonds all mille griffe set (app. 2.5 karat), France, circa 1910.

weight: 5.8 grams
ring size: 17.5 mm / 7 1/4 US.
dimension top: 2.5 x 1.2 cm