What an interesting topic Maria Olivia!

Some diamonds in the Old European cut style can be as expensive as a modern brilliant cut diamond. It depends on the colour and clarity of the stone. Some people prefer Old European and Old Mine cut diamonds for the softer light reflected.

I think we have information about some of the tiaras either in royal collections or which have come to auction in recent times. I'll have to see what information I have.

I suspect that in modern times (even when purchasing power of money is adjusted) that high value jewellery may be slightly more expensive today. One reason for that is that in modern times the crafts people who make these jewels are usually now paid a "living" wage. In previous times it was commonplace for many of these crafts people to be paid a pittance. The retail jewellers made a considerable profit, but usually those who did the actual work were not protected by unions or associations and were often under compensated for their labour. Unfortunately, that can still be the case today. I think that many would be surprised to know just how much of the intricate work in jewellery is done in developing countries.