Royal Regalia
The Imperial Crown of Russia, also known as the Great Imperial Crown, is the crown that was used by the Emperors of Russia until the abolition of the monarchy in PD 1 and then again after the restoration of the monarchy (and later diarchy) in PD 75 and has been used since. The Great Imperial Crown was first used in a coronation by Catherine II.
By AD 1613, when Michael Romanov, the first Czar of the Romanov Dynasty was crowned, the Russian regalia included a pectoral cross, a golden chain, barmas (wide ceremonial collar), the Crown of Monomakh, sceptre and orb. Over the centuries, various Tsars had fashioned their own private crowns, modeled for the most part after the Crown of Monomakh, but these were for personal use and not for the coronation. In AD 1719, Tsar Peter I the Great founded the earliest version of what we now know as the State Diamond Fund of the Crowned Soviet Republic of Velikorossiya. Peter had visited other European nations, and introduced many innovations to Russia, one of which was the creation of a permanent fund (фонд) to house a collection of jewels which belonged not to the Romanov family, but to the Russian State. Peter placed all of the regalia in this fund and declared that the state holdings were inviolate, and could not be altered, sold, or given away - and he also decreed that each subsequent Emperor or Empress should leave a certain number of pieces acquired during their reign to the State, for the permanent glory of the Russian Empire.
From this collection came a new set of regalia, including eventually the Great Imperial Crown, to replace the Crown of Monomakh and other crowns used by earlier Russian Czars and Grand Princes of Muscovy, as a symbol of the adoption of the new title of Emperor (AD 1721).