From the property of Mary Duchess of Roxburghe. Diamond ring, Cartier, 1930s. Estimate 8,000 — 12,000 GBP.  Lot sold 167,000 GBP. Photo courtesy Sotheby's

set with two pear-shaped diamonds weighing 2.31 and 2.34 carats respectively, further accented with two marquise-shaped diamonds, size L, signed Cartier London, case stamped Cartier Paris.

A photograph of Mary Crewe-Milnes before her marriage to the Duke of Roxburghe, age 19.

Mary Evelyn Hungerford Crewe-Milnes (named after her godmother Queen Mary) was born into a world of tradition and high society. Her mother was the daughter of a British Prime Minister and a Rothschild heiress, and her father was the handsome Earl of Crewe. Their homes were frequented by bright young things, politicians and the grandees of society. Mary, their only surviving child, inherited West Horsley Place in Surrey from her mother. 

Sotheby's. The Duchess Property & Precious Objects from the Estate of Mary, Duchess of Roxburghe London, 27 May 2015