The diamond and turquoise necklace is of stylised swag design, set with turquoise cabochons, highlighted with marquise, pear-shaped, brilliant circular single-cut and baquette diamonds. It was probably one of the private jewels of the Shahbanu Farah Diba.
It was seen when Farah Diba visited Emperor Haile Selassie of Ethiopia in 1968, at the state visit of Turkey and she wore it at the Near East Foundation dinner, in her honour, at the Waldorf Astoria New York in 1962 on the official visit of the Shah of Iran and his wife Farah Diba in America.
Above the Empress Farah, wife of the Shah of Iran, wears a large tiara with diamonds and pear-shaped turquoises and the matching pendant earrings. The parure, by Van Cleef and Arpels. had a larger turquoise and diamond necklace than the one in which the Empress is pictured above. Another tiara with smaller turquoises was sometimes worn by her.
The jewels of the Shah are deposited at the Bank of Iran, and they are owned by the state. Thank you to Volker who provided me with this information.