The Portuguese Diamond is an unusual octagonal-cut diamond known for its flawlessness and clarity. It weighs 127.01 carats (25.40 g) and is regarded as one of the world's most magnificent diamond gems.
The Portuguese Diamond gives out a strong fluorescence under ultraviolet light. Under daylight or artificial light, the diamond gives out a soft fluorescence and a beautiful bluish haze.
The name "The Portuguese Diamond" was given by Harry Winston, who previously owned the diamond.
According to one of the legends, the diamond was mined in Brazil in the eighteenth century and become part of the Portuguese crown jewels. But there is no documentation that proves this story true. Documented reports of the diamond state that the diamond was most likely found at the Premier Mine in Kimberly, South Africa, in the early 20th century, after which it was bought and owned by many people.
The first documented record of the diamond finds its ownership with the Ziegfeld Follies glamor woman named Peggy Hopkins Joyce who bought the diamond from Black, Starr and Frost in February 1928. She traded her $350,000 pearl necklace and additionally paid $23,000 in cash to purchase the diamond. She had the diamond mounted on a platinum choker that could be worn closely to the neck. In 1951, Harry Winston acquired the diamond from Joyce. The Portuguese Diamond was a part of his "Court of Jewels" until he sold it to an international industrialist in 1957. At present, the diamond belongs to the Smithsonian's diamond collection after they acquired the diamond from Winston, in exchange for 2,400 carats (480 g) of smaller diamonds.