Shapton glass color change

As some of you know, the glass hones come in 2 kinds: white and grey. The grey ones are meant for carbon steel such as knives and japanese tools.
I have no idea what the difference are and if they matter or not, but there are 2, and the grey ones are for Japanese stuff.

But in Japan, the most valued color of a natural hone is white, and many -including So- felt that it was a shame that the ones for Japan were grey.
I read on japan-tool.com that because of this, Shapton decided to make their hones for Japanese stuff from grey to white, or at least whitish.

So keep in mind, the color in pics is no longer an indication of the type of hone.

The new formulation for white and blue steels is much antisipated (by me :D ) and color is not an issue. I know that as soon as they are readaly available in the US, Dave will be calling me so I can order a set.