Welcome to SRP. How long is the return policy good for ? Do you have more razors to test the stone ? I wonder if the seller actually honed razors on it, whether it was tested by him with chisels or plane blades ? A lot of the J-nats are devoted to tool sharpening. Sounds like you know enough from your experience with your other hones to accurately gauge the efficacy of the stone. If it is at the 8k level I would certainly send it back and, if you haven't already done so, let him know that you intend to hone razors with the replacement. Also, if it was me I would go by actual sharpness rather than scratch patterns.