Franck, you asked about this before but I have just recently found a slightly clearer photo of the Duchess of York likely wearing the sapphire necklace described by Roberts:
Queen Elizabeth (when Duchess of York) used Sintzenich to make a new sapphire and diamond chain pendant in 1929.
I think it was most likely made from the wedding gift presented by Queen Mary.
Has anyone ever seen the bracelet? Perhaps it was used also. The large brooch was of course a favorite, worn throughout the Queen Mother's life, and the small sapphire brooch went to Princess Margaret.