Vlad Tepes / Vlad the Impaler / Count Dracula.
Vlad III, Prince of Wallachia (southern part of Romania), 1431-1476.
See: http://en.wikipedia.org/wiki/Vlad_the_Impaler
The painting probably present a jewel with pearls and ruby, mounted in gold, that (or a similar piece) could belong to him.
Note: for the curiosity of foreign readers of my blog it was NOT prince (voievod) Vlad Dracula that introduced first on our country the punishment by impaling, but prince (voievod) Stephen the Great / Stefan cel Mare of Moldavia, contemporary to / also enemy of him.
