This topic was started by Dmitry (far below), that prompted me to search in the Library of Congress collection. This was what I found several days ago. I am sure most, if not all, of you already had seen this picture of the whole array of Russian Crown Jewels on the table. I put here this whole picture, plus zoomed-up snippets of all portions of the whole table, starting from the left to the right.
There appears to be 13 tiaras in total in the whole picture. Question: how many of them ARE NOT in existence anymore or of whose whereabouts are currently UNKNOWN?
Source: Library of Congress, from the "New York Tribune" (NY) dated Dec. 17, 1922 (published on the front page).
The whole picture of the array of jewels and non-jewel pieces on the table
Caption:
From the left side to the right side (with upwards and downwards across the left to right sides):
The End.
It staggers me how many the Russian royal family actually possessed because there were a lot of other jewel pieces (pre-Russian Revolution of 1917) that were either carried into other European royal families via marriages, bought by some members of the other Royal Families (i.e., Britain), and smuggled out of Russia during the Revolution. Or lost during the transition out of that country.