3/$50 Vintage Green Art Glass Pitcher

This pitcher is in excellent condition. The last picture shows an imperfection in the base (could be its trademark?). I do not believe it is a crack as it feels perfect along the edge and on the bottom it is an imprint on the top. 13.5 in is its height and the widest part is approximately 4.5 in. it is dusty and needs a cleaning and I do not want to damage it so I am afraid to clean it.