Joan owned dozens of pieces of Faberge, some with a royal provenance. Much of her collection was auctioned at the Sotheby's Russian sale in April 2001.
Here are photos showing a few of her Fabergé pieces:
This article from The New York Times mentions "a Fabergé frame that the queen of Denmark had given to Queen Victoria." Could that be the frame on the bottom row? I have not been able to find any of the items on Sotheby's website. Perhaps someone has the catalog from that sale.
Not pictured is a Fabergé gold and enamel cigarette case which belonged to Queen Mary. Featuring the "M R" cypher, it was a gift to Melissa Rivers, Joan's daughter.
The article mentions that the objects were being sold so that she could "concentrate on Fabergé jewelry now," which has served as the inspiration for much of the costume jewelry sold on QVC in the past. So perhaps in due course we will see an auction of some of Ms. Rivers' Faberge and other fine jewels.