For your peace of mind, I would suggest getting one from someone who does test them extensively before offering them for sale (i.e. O_S)
Like Nelson said, these aren't for the uninitiated. A lot of times you won't know until you try it. I would say the same is true with a coticle too. Depenting on the size of the garnets and the softness of the matrix, you won't know what characteristics it has until you buy it and try it. (coticles are a little more consistant though) Most of the time it is a bit of a gamble. If you can spare that kind of cash then go for it.
This vendor does offer some input in to the characteristics of the hones through his HGAL ranking. I would keep that in mind.
Actually the one I got for my bro, I lapped and tried out on a couple of razors before handing it over. Although I think my skills at the time were lacking I would say that is was a very good final polisher. It was a mixture of greens and blues and a swirl of yellow. A very very beautiful stone. The colours weren't appearant when I bought it though. They came out stronger after I lapped it.
I also look forward to the new one on the way. I should have it by Thursday. :rock:
Also, it can't be said enough, no two natural hones are identical. Whether or not I got a good one or a bad one is irrelevant, the next one may be better than anything else. You won't know unless you try it.
:gl: