Rough Dimensions: 3-5/8" diameter & 2-7/8" tall
Makers Mark: unsigned
Condition: Very good, with a few minor marks to the upper surface and shelf wear to the flat polished base. Please see photos and let us know if you need any additional assistance.
Possibly Kit Karbler & Michael David Blake Street Glass but unconfirmed. Featuring an outer shell of a blue spiral and an inner shell of green spiral, a central control bubble and a small hole placed in the center of the underside.