Artworks by (left to right) Damien Hirst, Leyla Cárdenas and José Horacio Martinez line the entrance hall, painted Benjamin Moore Distant Gray, of a Key Biscayne apartment by designers James and Miriam Duncan. A vintage Louis XVI chair and custom gold-leaf-and-iron table rest on white-oak Duchateau flooring from Deco27 and near ABC Carpet & Home’s Color Reform rug.