Connoisseur

A connoisseur (French traditional (pre-1835) spelling of connaisseur, from Middle-French connoistre, then connaître meaning "to be acquainted with" or "to know somebody/something.") is a person who has a great deal of knowledge about the fine arts, cuisines, or an expert judge in matters of taste. In many areas the term now has an air of pretension, and may be used in a partly ironic sense, but in the art trade connoisseurship remains a crucial skill for the identification and attribution to individual artists of works, where documentary evidence of provenance is lacking. The situation in the wine trade is similar, for example in assessing the potential for ageing in a young wine through wine tasting.

"The ability to tell almost instinctively who painted a picture is defined [...] as connoisseurship". Connoisseurs evaluate works of art on the basis of their experience of the style and technique of artists. Judgment informed by intuition is essential, but it must be grounded in a thorough understanding of the work itself. On the basis of empirical evidence, refinement of perception about and form, and a disciplined method of analysis, the responsibility of the connoisseur is to authorship, validate authenticity and appraise quality. These findings are crucial for the valuation of works, and can be collected and organized into a catalogue raisonné of the work of a single artist or a school.

...
Wikipedia