Fine French violin by N.A. Chappuy or Chappuy school, late 18th century

A fine French violin made late 18th century. The violin comes with an appraisal letter and certificate from its previous owner appraising the violin at €9000 - €11000 and being made by N.A. Chappuy between 1750-1770. 
Our opinion is that we are not certain that the violin was made by N.A. Chappuy personally. The violin may be Chappuy School late 18th century. Therefor it is priced much more attractive than the value the appraisal states. The violin has a nicely flamed two-piece maple back and ribs and a fine-grained spruce table. The varnish of a dark orange-brown color.