OK, I've been dying to get a break and post my thoughts, since this morning when I read the story.
I strongly believe that the tiara in question is the Sapphire Bandeau, for multiple reasons.
1) the sapphire in the bandeau is interchangeable and Queen Mary
also wore the Bandeau with a carved emerald brooch from the delhi durbar parure. I know that journalist wrote 'emeraldS' plural, but I believe that to be a careless mistake.
2) the provenance of this Russian tiara IS a little bit sneaky. No one knows how Russian Empress Marie Feodorovna's tiara fell out of the empress's hands, when it popped up in Europe at an auction where Queen Mary allegedly bought it from Princess Nicholas of Greece (nee Grand Duchess Elena Vladimirovna). The dodginess of this tiara's provenance is very real, as is the fact that has an interchangeable emerald central setting. On the other hand, the Greville Emerald Tiara has very clear provenance, made by Boucheron in 1919 or 1921 for British heiress Lady Granville. As to the Vladimir emerald drop tiara, I think we can all agree by virtue of how much she wears it, that the Queen does not think that the Vladimir tiara is problematic. Also honestly, I cannot imagine Meghan or Harry seeing fit to demand it, and even if they did I do not think that the Queen would use provenance as an excuse for her refusing it.
3) Lastly, the filigree bandeau that Meghan wore and the Sapphire/Emerald bandeau are actually quite stylistically similar to my eyes.
Now as to why I believe the story about a tiara conflict in general:
1) Harry was with Meghan when she picked out the filigree bandeau, even admitting that "he shouldn't have been there". That he was there because of a kerfuffle and wanted to see through that Meghan ultimately got to pick out a (second choice) tiara that she liked goes a long way to explaining his self-admittedly highly unusual presence.
2) as I said, the filigree bandeau that Meghan wore and the Sapphire/Emerald bandeau are actually quite stylistically similar to my eyes. It is very plausible to me that the story is true because this tiara matches the description of what she allegedly wanted as well as what what problematic about it, and it is in keeping with the style of what she ultimately went with. Both are bandeaus of similar profiles, with geometric art deco designs emanating from a central brooch element. Plus, as someone else here commented earlier, the color palette of this wedding was exclusively white and green
3) Lainey Gossip, which is well connected to Meghan's camp and is also known in the gossip/entertainment industry for rarely ever getting it wrong, has thrown its weight behind this story. I highly recommend reading her post (and the other posts she linked within it) from today
(PS: Hi, Long time lurker making my first post!!! I am going to be posting up a storm over the next week of long pent up royal and aristocratic tiara discoveries and questions!)
I don't think that Meghan and Harry would be foolish enough to even contemplate the Grand Duchess Vladimir Tiara let alone Harry "hitting the roof" when told that the Vladmir was off limits.
My initial thought was that the tiara in question was the Queen Mary's Sapphire Bandeau tiara and they got the stone wrong, that tiara does have a questionable chain of ownership. When I had that thought it also popped in my mind that blue was a part of the color scheme but I went back and looked at the pictures and green seem to be the accent color.
Regarding the credibility of the article, Harry's is not above getting litigious, so I am going to wait and see if he (or Meghan) files an IPSO complaint.