This is some information about glass go stones I bought from Yutopian Enterprises. They are order number SK212, the 6.5-mm Korean stones. I put this here because it's hard to find information on go equipment on the web, and this may help someone.
Although I haven't bought any other stones, I think that these stones are the same as Kiseido's order number SK212, except that Kiseido says they will include plastic bowls. (Yutopian and Kiseido work closely together. Their ordering addresses are different suites in the same building.) I'll also bet that they are the same as Samarkand's #G1C.
I paid $19.15 ($13.50 − 10% discount + $7.00 shipping) for the stones. They arrived 15 days after I ordered them. They came in two white cardboard boxes 4 1/2 inches square by 1 3/4 inches high. Each box had a funny little half-inch square cut out of the center of the lid. The two boxes were inside a similar box that was twice as wide. Included were Yutopian and Kiseido catalogs and price lists. (They weren't the glossy catalogs you might be picturing. They were just photocopied individual sheets of letter-sized paper.)
On Yutopian's catalog page, the stones are advertised to be both 20 mm in diameter by 6.5 mm thick and 20–21 mm in diameter by 7 mm thick. I measured a few from my set. Both black and white stones are all almost exactly 20 mm in diameter. (I think that this is smaller than most stones. These stones look a little bit sparse on my boards. The thickness of the black stones varies between 7 and 8 mm, and the white stones are all about 7 mm thick.
I received 182 black and 183 white stones. About five stones of each color were noticeably chipped or warped.