After I looked more carefully at the photo Franck recently posted of Queen Mary in a rowing boat, I wondered if it is possible that the brooch HM wore at her throat is the same as the centre piece now used by Princess Alexandra on her pearls?



J-F has identified that Princess Alexandra originally wore the centre piece as a brooch http://mb.boardhost.com/historyroyaljewels/msg/1561986897.html

and that later she used it as a clasp for a long strand of pearls, and in recent years as the centre piece of her most frequently worn pearl choker necklace.
http://mb.boardhost.com/historyroyaljewels/msg/1561390996.html

Princess Alexandra showing centre piece of choker.



Detail showing Queen Mary's brooch


Could it be that it is light bouncing off the diamonds in the centre which makes Queen Mary's brooch look as if it has a larger stone in the centre? The rest, the shape and the pearls seem to match. Or am I imagining things?