A parure commissioned by an Ottoman Sultan was traditionally composed with the diamonds owned about 160 years earlier by an empress of Russia. Although that provenance was not accompanied by in period documents there is not any reason to have a doubt.
Marta Helena was an illiterate daughter of a Lithuanian peasant. This pretty girl had an early life of adventure, between soldiers and prostitution. She managed to be sold to one of the closest courtiers of Peter the Great. In 1707 the Tsar married her secretly. In 1705 her name had been changed to Catherine Alexeyevna.
The Ottomans declared war on Russia in 1710. Peter and Catherine went to war. The campaign of Pruth, ill-prepared, turned to disaster in 1711 on Russian side.
Fully understanding the Oriental traditions, Catherine, without informing Peter, joined her diamonds to a message prepared by the Tsar to propose peace. This present was decisive and the treaty was concluded. Catherine married Peter officially in the following year and was his successor as Catherine I at his death in 1725.
The sultans had treasured this tribute and the Ottoman prince who was to become Sultan Abdul Hamid II had it assembled in a necklace, a pair of earrings and a brooch, probably in 1874. This suite is made of diamonds of various colors, the most important being a 4.46 carat fancy intense yellow.
The parure passed at auction on November 15, 2011 by Sotheby's in Geneva. The estimate was not in the catalog, certainly due to a very high reserve price. It comes back in the same auction room on November 16, lot 328 estimated US$ 3M. The story above is mostly copied from my 2011 discussion.