carved in four strata, facing dexter, wearing a laurel wreath, the edge signed W.[eder] F[ecit]

Tiny losses at the back edge otherwise in excellent condition and very nicely carved.
"In response to your inquiry, we are pleased to provide you with a general report of the condition of the property described above. Since we are not professional conservators or restorers, we urge you to consult with a restorer or conservator of your choice who will be better able to provide a detailed, professional report. Prospective buyers should inspect each lot to satisfy themselves as to condition and must understand that any statement made by Sotheby's is merely a subjective, qualified opinion. Prospective buyers should also refer to any Important Notices regarding this sale, which are printed in the Sale Catalogue.
NOTWITHSTANDING THIS REPORT OR ANY DISCUSSIONS CONCERNING A LOT, ALL LOTS ARE OFFERED AND SOLD AS IS" IN ACCORDANCE WITH THE CONDITIONS OF BUSINESS PRINTED IN THE SALE CATALOGUE."

Master gem engraver Giovanni Battista Weder was born in Rome in 1742.  He is recorded as still living in Rome, at Piazza Navona 97, in 1808.  He is known to have worked for the Pope as well as the Russian Court, though it is unclear if he ever travelled to Russia.  An onyx cameo carved with a bust of Pope Pius VI and signed WF is in the Kunsthistorisches Museum, Vienna. 

The carving of the present lot, utilising four varying layers of agate in order to achieve a greater illusion of depth, is espec🦩ially adro♛it.