Hello Matt and welcome.
I had a quick look at your pictures and my first thought is bohemian/Czech, possibly Borocrystal as they did pieces with the painted crackle effect.
The base you describe sounds like a polished Pontil Mark, and you should find plenty of images to compare yours to.
I would guess c.1950, but similar styles were made over a long period. Wear marks on the bottom can be an indicator of age, but some pieces are kept in cabinets so an absence of marks does not necessarily mean something is modern. If you can identify a maker, it can help narrow down the date.