white or very pale seeds are generally immature ... seeds that take more than a few hours to absorb water and sink, are also questionable ... seeds that you can crush between your fingers are definitely no good ... other than that, most seeds look the same, and vary mostly in size only, you cannot discern strains by looking at a seed ... some believe the 'tiger-striped seeds' are the most potent, but I have seen no proof of that ... :smokin: