I have two large demijons - one about 24 inches, the other probably 18. The taller one is newer, I'm sure. The shorter one has no seams, no markings other than a pontil mark, lots of bubbles, applied lip, pale aqua colour.
The larger has a wonky seam on the neck, a different seam on the lip...
Sorry if this is a repeat, Folks, but I'm a bit new to glass...I have a demijohn that I've carted around for years, and just recently decided to look into its history. I'll post a pic if I can figure out how, but the details are this: hand blown, no seams, aqua (I think it's called) glass...