The Star of Adam is an oval shaped blue star sapphire, the largest star sapphire in the world. It weighs 1,404.49 carats (280.898 g), and its estimated cost is at least US$ 100 million. However, it expects worth at auction up to US$ 175 million. Prior to its discovery, the Black Star of Queensland, weighing 733-carat (146.6 g), was the largest star sapphire gem in the world. The blue color gemstone has six-pointed star-shaped reflection or distinctive mark in the center.
It was discovered in Ratnapura (known by nickname as the "The City of Gems"), in southern Sri Lanka in August 2015. It was named "The Star of Adam" by the current owner as per Muslim beliefs that Adam had arrived in Sri Lanka and lived in Adam's Peak after leaving Garden of Eden.
The current owner is not known since he was not willing to publicly reveal his name and stay anonymously, but told the BBC World Service's Newsday radio programme that
"The moment I saw it, I decided to buy", and added "this was not a piece of jewellery but an exhibition piece".
The blue star sapphire's weight 1404.49 carats was certified by the gemology institute, and the institute told that it never certified such gemstone larger than "The Star of Adam". A leading gem and jewelry dealer in the country told BBC and confirmed that it was the largest blue star sapphire in the world.Further an interview to BBC Earth, Simon Redfern, Mineral scientist from the University of Cambridge told that
"The stone could have formed within the granite rocks of Sri Lanka's highlands. It was able to grow so big because of constant but slow change in temperatures and pressures within the rocks for millions of years".