By possibilities I mean that there may be several answers to the mystery.

!. Leslie Field may be mistaken.

2. QEII may have 2 sapphire tiaras in her collection which are unknown to us.

3. One possibility is that one of the mystery tiaras may be the one worn by Queen Mary (and later by Princess Margaret) which had the large sapphire brooch in the centre.

It is an intriguing mystery! If any one is ever going to solve this for us, it will be Franck! He has been searching constantly for these tiaras!