Charll, George and Luke,
I've read that jet is very porous and expands and contracts with temperature and moisture changes. That could very well explain the pin head sized surface bumps.
I have several lacquer bottles - including one that is plain black lacquer. This bottle doesn't even compare - everything is different from specific gravity to texture to weight. I have yet to find a lacquer bottle that doesn't float. Their specific gravity is closer to 1.0 and you can only perform a specific gravity test if you force water into them. The jet one sunk right away.
Lacquer bottles don't have a grain. This bottle has a grain just like in the pictures Luke shared - you can see the fissures and grain are part of the surface, not beneath it. And also I did a hot needle test on the inside of the bottle - it smelled like coal.
I have read about efforts to pass off black lacquer as jet and as I mentioned I have one of those bottles to compare it with so the differences are easy for me to see. The black lacquer floats and it has no grain.
I searched the house and found some unglazed porcelain, and very much regret it. I did the scratch test and it left a brown streak but it also scratched the bottom of the bottle. Only after I did the test I read that unglazed porcelain is 7 on the Mohs scale, while Jet is a 3-4. So I'm regretting that very much - however, just polishing it with my eyeglass cloth has already improved the scratches I made.
Unless there is some other material that could explain these things, I'm considering it the genuine article.
I think I have the "soft" version of Jet that was formed in freshwater.
Update: since I had already scratched the bottom I went ahead and did a mohs hardness test. Fingernail - no scratch, Penny - no scratch, Florite - faint scratch - could still rub it out, I don't have apatite to test for 4 but a steel knife leaves a very defined scratch. So I can definitely say that the Mohs falls between 3 and 5.
