The story
Skinner & Co. was established in 1880. In 1893 Spencer Compton Cavendish, 8th Duke of Devonshire commissioned the jeweller to create a diamond coronet for his wife Louisa Cavendish, Duchess of Devonshire. She was seen as a leader of fashion and society, holding many balls at Devonshire House and was especially well known for the magnificent jewellery that she wore. In order to make the coronet the 8th Duke of Devonshire removed the diamonds in the Devonshire Parure and other heirlooms, such as the 6th Duke's Garter Star. These totalled 1041 diamonds, to which Skinner added another 840.
Bentley & Co. was founded in 1934. The two companies joined in 1997 creating Bentley & Skinner, Jewellers by Royal Appointment.
From Wikipedia’s article on Bentley & Skinner, shared under CC BY-SA 4.0.3