Can you show us the other side of the coin if the surface is not vanished? Keep in mind that the coins of Hungary or Bulgar also did mint similar scyphate (cup) coins like Byzantine, so I am not 100% sure that your is a Byzantine, but if it is then that is definitely from 1100c.e until 1300c.e.
It's Byzantine, but the reverse being so worn will make it tough to identify. Perhaps one of the Byzantine collectors will wander in shortly and have something more to help.
What is the diameter in mm at the widest point? If it is 30mm or so, it may be a billon trachy of Theodore I, Emperor of Nicaea, 1208-1222. The figures would be Theodore I on the left and St. Theodore on the right with a patriarchal cross between them (Sear 2061). If the diameter is 20mm or so, it may be a similar type struck by the Latin Rulers of Constantinople (Sear 2050). However, with one side worn and no visible legends, it's only a guess.
the diameter is 18.8. i dont know if it is rare i just would like to know exactly the emperor.i know that is hard with the one side no visible.
At 18.8mm, it is an anonymous coin of the Latin Rulers, 1204-1261. As far as I know, coins of this period are not attributed to specific emperors.
i make wrong.i am not an expert in coins i have simply only that coin.i tried to measure it but i make wrong i dont know to do it exactly.i try to find in internet ways to measure it but looks so difficult.
