It would appear that the reference to the opal necklace of 1854 might correspond with what we now refer to the as the Crown ruby necklace. (I still have strong reservations about whether the gems are rubies.)
Unfortuately, from what Nellie said Bury does not appear to shed any light on the tiara in the portrait by Barker, held by the National Portrait Gallery UK, which has been the subject of our discussions.
I don't have a copy of Munn - but from the quotes Nellie has given, I would understand that he has not given any additional information about the tiara in the painting by Barker. If he has, it might help with our discussion.
Hopefully, I will find his tome in a library - I have never accessed it, and going to a library would be quicker than trying to purchase it.