Ganna Walska sold many of her jewels at auction in 1971. Among them was a yellow briolette diamond of 96.62 carats. In the late 1920s it was mounted as a pendant by Cartier on a diamond sautoir.
After the 1971 sale the new owner had Van Cleef and Arpels set it as a pendant to a spectacular brooch.
Sotheby's auction catalogue (2013) shows how this jewel dismantles to form several others. It also gives an overview of life of Ganna Walska.
I especially enjoyed the 4th photo which shows the mechanism which joins all the parts to form the large brooch.
This Sotheby's site is also interesting http://www.sothebys.com/en/auctions/2013/magnificent-jewels-ge1305/magnificent-jewels-auction/2013/11/history-walska-briolette-diamond-1971-sale.html with slightly more history.