Two headpieces believed to have belonged to Empress Joséphine Bonaparte of France are set to go on sale at Sotheby’s after spending the last 150 years in a private collection.

The tiaras, made in Paris in 1808, are expected to fetch up to GBP 500,000 ($684,629) combined at the December 7 London Treasures sale, the auction house said last week. Each headpiece is part of a parure — a set of matching jewels designed to be worn together. They are still contained in their original Parisian leather boxes.

The first is a gold diadem decorated with blue enamel and carnelian — a semiprecious gemstone — and set with 25 engraved pieces featuring male and female classical heads. It will be offered together with a pair of pendant earrings, each set with a single intaglio — a type of engraved image — and similarly decorated. The set also comprises a hair comb and a belt ornament, the center of which has an etched cameo of Bacchus, the Roman god of agriculture, wine and fertility. The parure is estimated at GBP 200,000 to GBP 300,000 ($273,852 to $410,777).