Three types of valuation must be carried out for an appraisal to be comprehensive and professional.

First, provenance can provide important clues as to an artwork’s authenticity and value.

Second, stylistic valuation based on criteria commonly used in art history analysis gives experts the tools they need to give a credible opinion on the making, composition and materials of a piece.

Finally, scientific valuation, the only one that can be called objective, consists in a wide array of highly technological tests that allow a precise evaluation of the nature of the materials used and thus establish beyond doubt the authorship of a work or, on the opposite, have it withdrawn from an artist’s body of work.