Originally Posted by
DaveW
If the stone is relatively fine and hard enough to not slurry at all when you put clear water on it (and isn't scratchy), you'll be able to finish a razor on it.
There are a lot of stones on ebay that have nobody commenting on their hardness, though, nor fineness and they are being sold at what I'd consider to be dealer prices for a known stone.
I'm a big advocate of jnats, but they have to be awfully cheap to buy one that doesn't specify what it is. I know it's getting harder to find decent ones, but aframestokyo is a dealer I'd go to if I was looking to save money. Any of the razor sized and small bench stones that are $150-$300 with no information on ebay are to be avoided.
Anyway, use your stone, if it autoslurries it will leave a very hazy finish on the razor and an unsatisfactory edge.