Hi Robbo, & Lynne
Well most definitely it is not an exact science, however I collect the bubble based bud vases, and I have been trying to identify them. I now have well over 350 of them and through handling them one starts to notice they fall into different types. I am just starting to be able to guess where they were made, and am often (though not always) proved correct later when one with a label turns up, just by looking at the size of the bubbles, they way they are formed within the ball, the finish of the bottom of the base, the shape of the stem and even the colours. One thing I have noticed is that those with Czech labels usually have small well controlled bubbles arranged in a spiral although they do not usually have a cut flat and polished base as you said your pear did. However different items are often finished differently. My gut instinct when I looked at your pear was Czech, and although I don't often offer an opinion on this board as I am a novice collector of glass, I did feel confident to add my 'seconded' comment. Take a quick look at my site (link below) and you can see some examples of bubble styles there.