It is one of the biggest cut sapphires in the world, weighing over 300 carats.
It was bought at the end of the19th century by the Grand Duchess Maria Pavlovna of Russia, a passionate jewelry collector.
It was passed on to her daughter-in-law, the Grand Duchess Cyril. After the 1917 Revolution, needing money, she sold it to her sister, Queen Maria of Romania.
On her death it came into the possession of her daughter-in-law, Queen Helen of Romania, my first cousin and godmother.
She, in turn, was in need of money and sold it to the shipowner, Stavros Niarchos.
He then gave it to Queen Frederica of Greece, who wore it on my weddingday.
Since then, it has been sold again.