Francois-Regnault Nitot (1779-1853), drawing workshop, Drawing of half of the turquoise and bright band made for Marie-Louise Empress of the French, 1811, 21.2 x 32.5 cm. Pen and black ink, traces of black chalk, watercolour highlights on wove paper. © Chaumet Collection

Jean-Baptiste Fossin (1786-1848), drawing workshop, Preparatory drawing for naturalist jewellery, 1830-1850. Quill and brown ink on paper © CHAUMET collection.

Joseph Chaumet (1852-1926), drawing workshop, Preparatory drawing for a tiara with facing snakes surrounding an emerald, Ca. 1890-1900, 15.5 x 29 cm. Pen and black ink, traces of graphite pencil, gouache wash on cream tinted card. © Chaumet Collection

Joseph Chaumet (1852-1926), drawing workshop, Two sketches of bat tiaras, ca. 1890-1900. Quill and Indian ink, wash on tracing paper and gouache on card. © CHAUMET collection

Joseph Chaumet (1852-1926), drawing workshop, Study for a necklace that can be converted into a band tiara, Ca. 1905, 15 x 33.9 cm. Graphite pencil, white gouache, wash and highlights on black tinted card. © Collection Chaumet.

Joseph Chaumet (1852-1926), drawing workshop, Preparatory drawing for the project for a winged tiara delivered for Gertrude Vanderbilt, 1908, 15 x 16 cm. Graphite pencil, pen and grey ink, gouache wash on cream tinted card. © Chaumet Collection.

Joseph Chaumet (1852-1926), drawing workshop, Two projects of tiaras around a bundle of emeralds, Ca. 1910. Quill and black ink, white and coloured wash, wash drawing and soak on card. © CHAUMET Collection

Joseph Chaumet (1852-1926), drawing workshop. Preparatory drawing of Egyptian inspiration tiaras, ca. 1925. Graphite pencil, white gouache and highlights on card © CHAUMET Collection.

Marcel Chaumet (1886-1964), drawing workshop. Preparatory drawing for tiara with diamonds, sticks and circles, ca. 1940. Graphite pencil, gouache wash and highlights on card © CHAUMET Collection.