I'm not going to bore you with a full-on photo of a CD 152 Brookfield in Green. However I feel the embossing should be shown. What we think happened with this piece is that a little round rod of glass that had cooled had fallen onto the embossing and did not re-melt.

This insulator was found by John Wilson in Worcester, MA in the old Boston and Albany RR yard near the old Coca-Cola plant and the beautiful Union Station. (http://en.wikipedia.org/wiki/Union_Station_(Worcester,_Massachusetts)

Thanks for looking!