Does any one recognise the brooch QEQM wore to Ascot in June 1938?

Apart from the Hanoverian pearls the Queen was wearing her turquoise drop earrings (this is the second occasion I have identified). Her dress according to the press was ecru lace over pink.

I'll post all the photos I have found as the various angles may help -- but in some photos the brooch seems to disappear entirely.