As a new exhibition illuminates, van Gogh’s irises were originally purple. Titled “Ultra-Violet: New Light on Van Gogh’s Irises,” the show is the result of “conservators and scientists ...

Van Gogh paired opposite hues on the color wheel with one another, first testing pairings with yarn to avoid wasting paint. Purple and green are “opposite-ish” on the color wheel, Ormond noted ...