Pigment analysis of portrait miniatures using Raman microscopy

✍ Scribed by Alan Derbyshire; Robert Withnall

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 833 KB
• Volume: 30
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/(sici)1097-4555(199903)30:3<185::aid-jrs357>3.0.co;2-u

✦ Synopsis

Raman microscopy was used for the in situ identiÐcation of pigments and covers of a glazed portrait miniature of Elizabeth I, namely the Armada Jewel, otherwise called the Heneage Jewel. It was conÐrmed that the gemstones on the frame are diamonds and rubies from their characteristic Raman and Ñuorescence spectra, respectively. The domed cover on the front of the locket was identiÐed as a-quartz crystal from its Raman spectrum, whereas the Ñat 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 through the amorphous glass cover. Nine di †erent pigments were unambiguously identiÐed : white lead, vermilion, red lead, azurite, lazurite, orpiment, pararealgar, yellow ochre and malachite. The Raman spectrum of a further, unidentiÐed green pigment exhibits a band of medium intensity at 969 cm-1 and weaker bands at 596, 546, 476 and 388 cm-1. It was shown that this pigment is not chrysocolla, atacamite or pseudo-malachite by comparison of their Raman spectra. Finally, the brown pigment used as a dark tone contains amorphous carbon.