An intriguing question Lorenzo. Except for the photo showing the turquoises, the Duchess looks older than when some of her jewels were stolen in 1946.
I wonder if it is possible that she quietly sold the jewels to a jeweler?
In his book on Van Cleef & Arpels (pp 43-44) Vincent Meylan relates an incident where the Duchess, having been insulted by Sita Devi over a necklace previously owned the latter, returned it to the jeweler the next day. Until publication of the book few would have known of the incident.
The Duchess may have given some jewels to close friends (she is said to have given a brooch and earrings to Princess Michael) or her lawyer may have sold some quietly to provide money for the Duchess' nursing staff. The lawyer is said to have sold some valuable china for this purpose.