This is one of the great mysteries Dave.

Bryce's opinion is certainly the impression which Hugh Roberts gave in The Queen's Diamonds

My own opinion is that, as QEII used the diamonds from the Niazam tiara to make the ruby tiara, even the frame may not still exist. But Roberts was not explicit on that issue, so perhaps the frame still exists. I doubt it, but we may yet be surprised. And what a pleasant surprise -- as you suggest-- it may be!