Thanks, Nellie, I did spend a few hours going back and forth between different texts, photos, and captions. I wanted to get a clear picture of the evolution of these tiaras.
I made a few corrections after I posted, but they were mostly matters of odd wording that I did not label as Edit. If content changes, I will so label any changes.
You may be right about Princess Margaret and the Teck tiara. Maybe she only wore the necklace, which remains with her son. I'll keep looking for pictures, as I seem to remember her wearing the tiara. No one has worn it much since Queen Mary's mother wore it herself. I wonder how comfortable it is.
I was sorry there was not a picture of Princess Anne wearing the Fringe tiara. Odd, since I believe Roberts included a picture of Diana in the Lover's Knot tiara. It seems as though these tiaras should be traced through the family in photos as well as text.
That's why I would like to see coverage of the Queen Mary tiaras which went into other branches of the family. Other jewels, too, for that matter. The Teck circles or hoops necklace is barely mentioned. It has been worn much more often than the tiara, though not by the Queen.
Thank you for posting more comparison photos of the Delhi Durbar tiara. My impression is that Roberts either was not terribly interested in the development of that tiara, or found nothing to report. You'd think there would be notes from Queen Mary and the jewelers. But he says her records end in 1939, and Queen Elizabeth wore the tiara in 1947. Judging by your photos, the top of the tiara was altered after that. So perhaps records are missing or sketchy.