Value, Worth says, is determined by taste first and foremost—if a client doesn’t like it, he shouldn’t buy it.

The next step in assessing value is monetary. “Prices are established by galleries, but that doesn’t mean an artwork is worth that amount,” she says. Whether a piece is accurately priced comes down to some combination of an artist’s gallery shows (“Ideally you’ll see multiple shows on multiple continents”), how much the work sells for on the secondary market, and “how the art fits into the art historical canon.”