Actually Belorussian, the early style of HEMAH (C3H) with the "Niemen notches" on either side of the dome. This style is from the late 1940s-1950s. The base is rather badly chipped on this one.

"Purple-pink C3H Belorussian insulator with the C3H in a circle, lll on side dome and the lower Stolle Notch on side groove. These insulators were the result of the original J Stolle Neimen molds being salvaged and re-marked after the Soviet takeover of the glass factories in Poland.

The lower notch is the J Stolle Trademark reminiscent of the era."