Copies, Ricordi, and Replicas
A copy is an exact repetition of another artwork in the same medium as the original. The more faithful the imitation of the original in proportion, detail, size, and materials, the more truly a copy embodies the definition of the term. A replica is a nominally perfect copy, generally executed by an assistant or the master himself.

For a variety of reasons certain artists kept careful records of their completed work. In the spirit of the medieval model book, some artists made (or instructed their assistants to make) finished copies of their modelli for their own reference or for the training of pupils. Sculptors in particular used drawings to record a finished work in detail, since the expense of making and keeping a finished cast in their studios could not be justified. These drawings are called ricordi. They often include measurements and fine surface details that could not be recorded on a wax or terra cotta bozzetto in the round.
 


Pierre Biard II. Ricordo of the Monumental Bronze, Galatea. Musée du Louvre, Paris

 

by Michael Miller
Information supplied by: http://www.nyu.edu/classes