Red Cross
The cushion-shaped, 205.07 carat (375 carats rough), canary yellow Red Cross emanated from the Kimberly mine in South Africa. The diamond was presented as a gift to the art sale held by Christies London in 1918, on behalf of the British Red Cross Society. It was sold for £35,575 and was the highlight of the sale.
Perhaps the diamond should have been named the Maltese Cross as the Maltese Cross is clearly visible on the table facet of the diamond.
It was believed that a member of a European royal family had bought the Red Cross, however it was put up for auction in 1973 by an undisclosed American businessman. It was passed in at £820,000. The price it was expected to reach was £2,000,000. It was put up for auction again in 1977 but it is not known whether it sold. The identity of its present owner is unknown.
https://www.langerman-diamonds.com/encyclopedia/history-of-natural-color-diamonds/famous-color-diamonds/redcross.html