The blue enamel oval plaque, set with rose-cut diamonds, the largest to the centre, all in closed-back settings, ring size 7 Weight: 9.20gr.

In the second half of the 18th century, rings with a midnight-blue enamel background studded with diamonds became increasingly popular. Marie-Antoinette, after her coronation in 1774, wore a copy of this jewel, as evidenced by Adolph Ulric Wertmüller's painting of her with her children in the gardens of the Trianon at Versailles.