Even English cabinetmaker Thomas Sheraton endorsed the “agreeable effect” that convex mirrors had “on the perspective of the room in which they were suspended.” The form first appeared on palace walls in Northern Europe during the Renaissance.

The classical convex mirror, popular on both sides of the Atlantic in the 19th century when it became more affordable, currently poses a real buy opportunity for collectors. Today, prices begin at about $1,000, depending on age, condition, and decorative elements. “It’s a lot of bling for the buck,” says Leigh, pointing out that the best bulbous mirrors include branched candleholders, which substantially increase value (as well as change the name to “girandole”). “Armless, the mirrors are worth a lot less,” he says.

The mirror shown here is an English import. “Convex glass wasn’t made in America in the early 19th century,” notes Leigh. “England shipped the glass to America.”