Pigment analysis of portrait miniatures using Raman microscopy

Raman microscopy was used for the in situ identification of pigments and co vers of a glazed portrait miniature of Elizabeth I, namely the Armada Jewel , otherwise called the Heneage Jewel It was confirmed that the gemstones on the frame are diamonds and rubies from their characteristic Raman and fluo rescence spectra, respectively. The domed cover on the front of the locket was identified as a-quartz crystal from its Raman spectrum, whereas the fla t cover on the reverse side is an amorphous glass. The Raman spectra of the pigments were collected in situ by focusing the incident laser light throu gh the amorphous glass cover. Nine different pigments were unambiguously id entified: white lead, vermilion, red lead, azurite, lazurite, orpiment, par arealgar, yellow ochre and malachite. The Raman spectrum of a further, unid entified green pigment exhibits a band of medium intensity at 969 cm(-1) an d weaker bands at 596, 546, 476 and 388 cm(-1). It was shown that this pigm ent is not chrysocolla, atacamite or pseudo-malachite by comparison of thei r Raman spectra. Finally, the brown pigment used as a dark tone contains am orphous carbon. Copyright (C) 1999 John Whey & Sons, Ltd.