Sir Francis Drake's ring was a silver, engraved ring, which was worn by his self-proclaimed descendant Nathan Drake, who wore it around his neck by a lanyard.
The ring was also a makeshift key to decode Enochian script using the cipher disk.
The main inscription on the ring is "Sic Parvis Magna". According to Nathan Drake, this was Francis Drake's motto, which means "Greatness From Small Beginnings".
The date inscribed on the ring is the 29th of January 1596, the day after Francis Drake supposedly died. This is what made Nathan believe Francis Drake faked his death.