12 May 2017, 16:55 GMT
This valuable discovery was found by an amateur diver who was sweeping the Yauza River bed with a search magnet; the coin was stuck to a metallic pivot buried deep within the silt.
The coin turned out to be a gold ugorsky chervonets minted during the reign of Russian Tsar Boris Godunov (1598-1605), TV channel Moscow 360 reports.
Such coins weren't used as currency but were issued as a reward for martial valor. It is considered extremely rare, as only six such coins have been found to date, and may be worth over $17,000.
Meanwhile, the lucky treasure hunter opted to remain anonymous, because per Russian legislation a person who engages in archaeological activities without proper authorization and inflicts damage to artifacts during the process may face a hefty fine and up to four years in prison.
