I can tell a cannabis seed from a beet seed or pumpkin seed but not much beyond that. If you already know what a seed from a certain plant looks like you can tell some from another. My Super Silver Haze are tiny and evenly colored, my bubblegum are normal sized and striped/mottled and one of the other strains are extra large, evenly colored grey. But I don't think these characteristics hold true from one phenotype to the next.