A recent ruling by the French Supreme Court answers the questions of when it is acceptable to call a reproduction of a scuplutre an "original".
In the May 4, 2012 decision the Court was asked to rule on a dispute between heirs of renowned sculptor Camille Claudel. The heir holding the right of reproduction (in force until 2013 as the artist died in 1943) had issued a certificate of authenticity charcterizing a certain reproduction of the sculpture ("La Vague" or "The Wave") made after the artits's death as an "original work of the artist".
Heirs holding the moral rights (which are perpetual) took issue with this, alleging that such a characterization was a violation of the right of integrity. The Court agreed, holding that only those limited edition bronze proofs cast from plaster or in clay made by the sculptor personally such that in their very execution they bore the stamp of the author's personality could be characterized as originals as distinguished from mere reproductions.
The decision is noteworthy both for the very clear crietrion set out for the proper characterization of sculptures (and, presumably paintings and other such works) as "originals" as well as for the legal grounds used to protect against mischaracterization, viz. the right of integrity.
La Vague by Camille Claudel:
The full text of the decision can be found here (in French): http://www.legifrance.gouv.fr/affichJuriJudi.do?oldAction=rechJuriJudi&idTexte=JURITEXT000025807658&fastReqId=1752951674&fastPos=1