Dark striped seeds are supposedly mature and pale ones immature, but I have had pale autoflower seeds crack in a day and tiger striped ones do nothing. Colour and size mostly reflect the mother plant and the strain, not viability, so sorting a pack by appearance before germinating is a waste of time. A small test someone documented on https://turboautoflowerseeds.com (https://turboautoflowerseeds.com) tracked 40 seeds by appearance and found no useful correlation with germination. The only real check is putting them in a warm wet towel and waiting.