The Williamson Diamond brooch
Cartier
The central diamond of 23.6 carats is the finest pink diamond in existence. It was excavated from the Mwadui mine in Tanganyika (Tanzania) belonging to the Canadian geologist Dr John Williamson, who gave it as a wedding present to Princess Elizabeth in 1947. It was cut by Briefel and Lemer of London in 1948 and set in the centre of a new brooch designed by Frederick Mew of Cartier in 1952.
Williamson Pink
The Williamson Pink
The Cartier designed floral brooch contains the 23.6-carat pink diamond and baguette diamonds given to The Queen by Dr Williamson.
The famous Williamson Pink (54.5 carat rough) [ 142 carat's = 1imperial oz] was found on the surface in 1947 by some black boys here at the Williamson Diamonds Mine, Mwadui, Tanganyika (Tanzania). They took it to the Doc's house. Dr Williamson gave the priceless cut Pink round [23.6 carat] to the then Princess Elizabeth as the centerpiece of a floral brooch for her forthcoming wedding to Prince Phillip.

Williamson Diamonds Mine. Mwadui.