David Rago began selling American art pottery in 1972, entered the auction world in 1982 and founded The Rago Arts and Auction Center in 1996. This fall, the auction house enters its third decade in business with a season defined by strong private owner sales and singular objects. Among the private collections coming to market: In October, the best collection of work by George Nakashima still in private hands; contemporary glass from the Estate Collection of Nancy Connolly; and Jerome Shaw’s collection of decorative arts from Tiffany Studios, Art Nouveau objects, French glass and ceramics.