Antique olive oil cruet bought in Greece

Hi!

In a recent trip to Athens I bought this cruet in an antiques shop and I am trying to find out how old can it be. It is a bit complicated for me to get information of antiques in that side of Europe. From what my inexperienced eyes can tell I found no actual cruets with that characteristics, the glass makes some lines which appears to be handmade (maybe?) and the painted flowers remind me to the 20's-30's Greek designs. Any help?

I also wanted to know if you can tell me how can I clean it without damaging the paint or if I should clean it at all (I am a bit cleaning obsessed
:p)

Thank you in advance!