Alexander Kellum, a Brooklyn artist, is director of specialty finishes at EverGreene Architectural Arts. EverGreene executed the gilding on the president-elect’s latest project, the Trump International Hotel in Washington, in particular its 13,200-square-foot presidential ballroom. To quote William Shakespeare, “All that glisters is not gold.” The ballroom’s gilt is composition leaf, a copper alloy with only trace amounts of gold, a variation of which gilders call brass leaf. Brassy, yes. Gold, no.

“Real gold leaf in this situation would be a 60 to 80 percent increase in cost,” Mr. Kellum said, declining to discuss actual pricing. EverGreene also gilded Mr. Puryear’s “Big Bling” and has worked on residences and hotel spaces at the Plaza in New York (23.75-karat gold).

Image Castings by P.E. Guerin made for Henry Ford’s home in Dearborn, Mich. Credit... Fred R. Conrad for The New York Times

Michael Kramer, president and founder of the Gilders’ Studio, a company in Olney, Md., that gilded the William Tecumseh Sherman monument at the entrance to Grand Army Plaza in Central Park, estimated the cost of using brass leaf at roughly $2 a square foot, excluding installation. Gold leaf could run $25 to $35 a square foot.

Gilding is a topical application of precious metal to an object. In Gouthière’s workshop, gilt was applied with fire gilding, a process by which an amalgam of mercury and gold was gently baked onto an object in a low fire, the mercury evaporating and the gold remaining as a coating of gilt. Electroplating — using an electric current to adhere the gold to the object — appeared in the 19th century, largely replacing fire gilding, whose mercury fumes are highly toxic. Fire gilding, specifically, is now rarely used except in museum-piece restorations.