Are Ground Glass Joints Standardized?

[Puget]

I'm a GonG (Glass on Glass) newbie. Are the 14.5mm and 18.8mm ground glass tapers an industry standard? The reason I ask is sometimes I see 18mm and 19mm listed, even on the same site.

I recently bought a Wildrose beaker from Grasscity and the downtube is loose and wobbly. Really not the quality control I was expecting for "made in USA" but I'm waiting to hear from Grasscity customer service. I tried the downtube from my Magic Glass piece and the 18.8mm fit is perfect (and almost an inch longer besides).

 

[Nycdeisel]

18 is really 18.8, so some people round it up to 19 and call it that. I would just call it 18.

same with 14, some people round up and call it 15. there is a standard. however, on rare occasions, small features of the glass could present problems in mating two pieces or attaching adapters.