Sotheby's to sell sapphire from the collection of the Imperial House of Romanov The auction will take place on November 11 in Geneva. The gem is valued at approximately 850 thousand - 1.7 million Swiss francs. The website of the auction house says that the sapphire weighing 197.8 carats is set on a diamond bracelet. This type of stone was purchased in 2015. It was originally the work of Carl Fabergé and was worn by Empress Dowager Maria Feodorovna, wife of Alexander III.