John Francillon

John Francillon (1744–1816) was a jeweler and lapidary, an English naturalist and an entomologist of Huguenot descent.

Francillon was a London jeweller who was also a dealer in natural history specimens and paintings. He was the agent for John Abbot selling his American bird and natural history illustrations. He maintained a large insect collection. Some of his butterflies appear in the Icones of William Jones. He was a Fellow of the Linnean Society.

In September 1812 Francillon was allowed to trace around an unset 45.5-carat (9.10 g) blue cushion-shaped diamond in the possession of the diamond merchant Daniel Eliason. Francillon drew the diamond in plan and elevation, coloring the plan drawing to match the deep blue color of the stone. Below the drawings he wrote notes to explain that he had been given permission to draw the gem by its owner, Eliason, and that it was " ... a very curious superfine deep blue Diamond."

"There is other evidence which places a 44-carat blue diamond in England at least as early as 1812." George Frederick Kunz, a distinguished American gemologist, told of finding two detailed sketches of the Hope Diamond made by a Soho lapidary in 1812. As he explained in an article in the Saturday Evening Post, Kunz discovered the sketches in an old book by Pouget that he found one day while browsing in Quartich's bookshop in London.

It is now known that this rare blue diamond was once part of the missing Royal and Imperial crown jewels of France. It was commonly known as the French Blue and had been set into Louis XV's jeweled insignia for the Order of the Golden Fleece. The French Blue had been stolen on 11 September 1792 along with most of the French Crown Jewels and was never recovered.

...
Wikipedia