The cuirass indicates that the nereid is bringing part of the second set of armor to Achilles. The surface preserves traces of gilding.
Metropolitan Museum of Art. 2003. "One Hundred Thirty-third Annual Report of the Trustees for the Fiscal Year July 1, 2002 through June 30, 2003." Annual Report of the Trustees of the Metropolitan Museum of Art, 133: p. 23.