Eagle eyed Emeraldeyes you are clever! It does look like the same thing to me!
I haven't got my copy of Geoffrey Munn's book as it packed away in a 'moving' box unfortunately, but I do not recall seeing it being written about in there, though it has been ages since I last drawled over the pages of that ravishing book!
I would love to know more about this tiara cum necklace...! I shall scour the Jewel thread again and have a really thorough look!