René Morin joined Chaumet as artistic director in 1962 and led its design through what the house now calls its golden age, from about 1965 to 1985. He was a keen gemmologist and a hunter, and drew on rough and hard stones such as lapis lazuli, malachite, tiger's eye, slices of tourmaline and turquoise; a pineapple parure of 1977 in turquoise and diamonds is among his pieces. With Pierre Sterlé, who designed for the house from 1961, he brought a modern play of volume and texture to Chaumet's work, with carved hardstones and gold that was hammered, cracked or textured, as in his Pierre d'Or collection.
When the house opened L'Arcade in 1970, a new kind of shop that was part jewellery gallery and part cabinet of curiosities, he made five oversized parures for it in textured yellow gold, known as "poli Arcade". He designed a bestiary of thirty-seven animals with the crystal maker Baccarat in 1970 and 1971, and creatures such as panther, snake and duck necklaces. He collected snuff bottles and Japanese sword guards, both of which became subjects of exhibitions at L'Arcade.
His most lasting design is the Lien ring of 1977, a band encircled by a gold loop at its centre, which grew into the Liens collection: diamonds and white gold followed in the 1980s, a cross in the mid-1990s, a diamond-paved link in 2002 and Premiers Liens in 2007, and it remains one of the house's three signature lines. In the 1980s he drove a revival of precious objects, famously carving a bull's head from a block of lapis lazuli. In 2023 Chaumet devoted the exhibition Un Âge d'Or: 1965–1985 at 12 place Vendôme to this period, with help from his widow.
Casadi has not verified his dates of birth and death or when he left Chaumet.