High Quality Content by WIKIPEDIA articles! The Constantine ruble is a rare silver coin of the Russian Empire bearing the profile of Constantine, the brother of emperors Alexander I and Nicholas I. It was prepared to be manufactured at the Saint Petersburg Mint during the brief Interregnum of 1825 but has never been minted in numbers and never circulated in public. The fact of its existence, classified in Russia until 1886, leaked into European press in 1857.