Hey Andrew,

What a great thread.

I'm going to drill this down by sale factor.

I think there is a huge number of factors involved like full provenance, familiarity, the stones then overall appeal. However I think stone quality is not a huge factor in actual price as hardly anyone would buy to break up to use the stones these days. However most royal tiara's at the time would have had a very high quality stones for the era not for our time. The real pearl factor would be a huge value factor.

For me I'd say the most valuable tiara in QEII tiara collection is the GGBWI as it's most associated with her but outside of people like ourselves the provenance wouldn't be well known. Though these things are becoming more well known through papers like the Daily Mail doing more jewel articles and segments to royal coverage.

I'd then go the Vladimir, though it may pip the post due to it's history and rarity especially if both pearls and emeralds were included. How many Romanov tiara's are still in existence period? Then add in it's very appealing history.

There is also a time factor say the GGBWI came on the market followed 5 years later by the Vladimir I'd then say the Vladimir would then definitely go for more.

Lovers knots because of the POW would beat the QA kokoshnik.

The Brazilian tiara would come last i'd say because it's not well known, doesn't aesthetically have a wide appeal and the aquamarines being a less sort after stone.

In terms of pure stone quality I'd the say the ruby and diamond tiara tops the charts as the it's most recent piece with stones that were better cut.

All in my honest opinion.