Art prices have been skyrocketing in recent years, and not only in the case of works by the old masters. “Boosted by an influx of Asian buyers keen to hoover up the classics of the modernist canon, the recent sales at Sotheby’s and Christie’s in London broke many records,” and the new high water marks likely won’t last long. But commerce aside, assigning value to art is a tricky business, especially in the long term, because “by far the most important factor in making art works valuable is what experts say and write about them.”