My Great Aunt's Lamp - looking for any info.

I have a large (aprox. 18" H) very old lamp that belonged to my Great Aunt, I believe it was orignaly a vase that was converted at some point. It was purchsed in the 1940s by my aunt from anitique store. Its in great condition, the front has a scene with two women and sheep, with a farm house in the background. The back is blank in that colbolt blue color. If you have any information on this peice as far as a possible maker, time period and possible value, it would be greatly apprecaited