A very savvy art trader, from a long line of private dealers, once said that a clear sign a work was for sale was one when a collector showed him around the house and would stop in front of particularly good piece. Without being asked, the collector would praise the picture and then add, ‘Of course, I would never sell it.’

That story comes to mind after reading Bloomberg’s nice piece promoting Emmanuel Di Donna’s show inaugurating his new gallery on Madison Avenue in New York. The show features works that are not for sale from several private collections, including a Clyfford Still painting, 1945-R, owned by Len Riggio:

“We look at it long term,” Riggio said. “I can tell you right now that my piece is not for sale.”

A quick review of auction histories shows that at least three of the works from the show are owned by the Nahmad family. Whether they’ve been borrowed to add an exceptional level of quality to the show or to provide the family with an additional sales outlet remains the intriguing question of the show.

The show culminates with a yellow Rothko displayed alone in its own room with exquisite lighting that brings out the subtle shifts in color and Rothko’s individual brushstrokes. The painting looks far better than it did when Sotheby’s showed it as part of Bunny Mellon’s collection and David Nahmad bought the work for $36.5m.

In addition to Riggio, Rothko’s daughter and the Perelman family of Philadelphia are mentioned as collectors. The rest of the works, including two Malevichs that are known to be the Nahmad’s, are listed as coming from private collections.

The Nahmad’s role in the art market has more often than not to be a provider of liquidity in down markets and a seller in up markets. When the Mellon works sold in 2014, the market could hardly be described as down. Nonetheless, David Nahmad plays a long game. Buying that Rothko and having it shown to good effect only shores up the painting’s long term value. Of course, he’d never sell it.

Masterpieces Missing at Auctions Turn Up at $450 Million Show (Bloomberg)