More than 40 pieces of jewellery from her collection will go under the hammer in London on June 11, the highlight of which is a pear-shaped, 38-carat D colour potentially flawless diamond which Onassis wore on a diamond pendant necklace.
It is expected to fetch between 1.8 and 2.2 million pounds.
Other important pieces in the collection are a rare bowenite Buddha by Carl Faberge estimated to be worth 250-350,000 pounds and a sapphire and diamond necklace by Harry Winston estimated at 120-150,000 pounds.
Christina Onassis, after whom Aristotle’s famous luxury yacht was named, saw her father, brother and mother die in a period of just 24 months. She died aged 37 after a history of drug abuse, weight problems and four failed marriages. She had a daughter, Athina, who was three years old when her mother passed away.