Contributed by Jeffrey Grunthaner / Properly curated, summer group exhibitions can open novel avenues between disparate artists and particular creative practices. “Made in Cologne,” currently up at Peter Freeman, Inc., decidedly accomplishes this. The conceit of the show is simple: the 15 featured artists have all made ceramic works at the atelier of Niels Dietrich in Cologne, Germany. Founded in 1984, Dietrich’s studio specializes in ceramics and showcases how plastic this medium can be. The expressive character of the exhibition derives in part from the variety of styles and attitudes on display. But all embrace the unique nature of ceramics in one way or the other.