Finally it got safely to my place, it has already been lapped and I have a healthy, perfectly flat 5mm of yellow and 9mm of blue layer - it's really a nice pocket hone, measuring 30 x 125 mm. Also, a full nickel bag of pure, fresh, white powder!
This is how it all looked in progress, sorry for this pitiful quality, I left my DSLR at my girlfriend's home. I will post better pictures later, maybe then it will be possible to determine layer from which it was cut.
BTW, I found out that I hate
lapping. It felt like I was scratching my favourite CD, or scratching my camera lens, or I don't know... Although I knew it was necessary, it still felt bad... And the worst was the very ending! when almost entire surface is lapped, apart from the last places that fall below surface and you just imagine how many razor strokes you lose with each move against the sanding paper... :scared:
<edit> Oh yes, near the bottom hand edge you can see a pile of blue powder, I don't know if it will be of use, but I collected it anyway.
Luckily, it's over. :thumbup: