The art of painting on enamel, invented in Blois, reached its zenith in France in the third quarter of the 17th century. Owners treasured the finely painted cases, masterpieces in their own right, but found the movements became dated after the introduction of the balance spring in 1675. Hence, many Blois watch cases were subsequently converted into snuff boxes during the 18th century and sometimes the backs and covers were preserved for their beauty alone. By the addition of precious stones to both frame and dial, Van Ceulen created a watch incorporating an earlier panel, as luxurious and spectacular as the original would have been, but technically more advanced. Robert Vauquer (1625-1670) was born in Blois, the son of a clockmaker and metal engraver. He served his apprenticeship with Morlière. He and his brother Jacques, who was an engraver, lived and worked their entire lives in Blois. Vauquer was much respected by his contemporaries, Félibien and Bernier greatly praising him, as did Dom Liron in his " Bibliothèque chartraine ". The abbé de Marolles said "As for Robert Vauquer, his work pleases us". A round watch, with the Holy family as principal subject, along with the Christ child, and incidental hunting scenes, signed " Vauquer pinxit ", is said to have belonged to Anne d?Autriche. A series of paintings on enamel representing scenes from the Passion, signed " Robertus Vauquerius Blesensis ", can be admired in the numismatic cabinet of the Vatican, a gift of Pope Leon XII.