Posted by Baxter on July 20, 2014, 12:39 am, in reply to "Re: Durbar Tiara"
Nellie, the photo to which you linked (below, right) is from the same sitting as the one on the left (although Queen Mary's face was not retouched!) where the squared shape of the stone is more apparent.
The Koh-i-nur is much larger than the Cullinan IV, as can be seen here in the crystal replicas now mounted in Queen Mary's crown.