The Collaborative International Dictionary of English v.0.48:

Virtu \Vir*tu"\ (?; 277), n. [It. virt[`u] virtue, excellence,
   from L. virtus. See Virtue.]
   A love of the fine arts; a taste for curiosities. --J.
   Spence.
   [1913 Webster]

   An article of virtu, or a piece of virtu an object of art
      or antiquity; a curiosity, such as those found in museums
      or private collections.
      [1913 Webster]

            I had thoughts, in my chambers to place it in view,
            To be shown to my friends as a piece of virt[`u].
                                                  --Goldsmith.
      [1913 Webster]