He plucked the cigarette from his mouth to tilt his glass back and take a drink. He hadn't quite expected that response, but it was an amusing one. John just smirked and chuckled, placing the cigarette back between his lips.
"It's a minor demon containment vessel. Or it will be when I'm finished" he said, picking up the etching tool he had been using. He started to scratch away at the glass again. Just a few more lines and he'd be finished. "I'm sure you can figure out what means. It's powered by the seal etched in the glass and a few words of power. It's not your typical Solomon seal. A minor seal with some Enochian script to add a bit extra power" he explained as he finished his work.
He stubbed the cigarette out and put the etching tool down. Placing his hand just above the seal he had working on, he closed his eyes and softly said, “B'koakh Shlomoh kvosh et hakhoshekh”. The markings lit up briefly, a sound like singing crystal resonating and fading to silence.
"There, all done" he smiled, quite chuffed with himself as he placed it back on the bar.