Thank you very much for your information. I was really convinced of its Persian origin.
I have checked both georgian and armenian alphabets -
looking at the cartouche placed in this position:

the cartouche would yield the armenian letters YKB or possibly YLB. The letter in the middle was not 100% identical with contemporary letters.
In georgian alphabet the first letter would be identified as V, but I was not able to identify the rest 2 letters.
What could these letters mean?
Initials of the maker?