I forget what its called, but one of those magnifying glass type eye pieces allows you to look at the color and clairty of the trichomes - I'm not positive, but ive heard that the darker colored trics earlier in the growth cycle give more of the indica effect, and when left to grow longer, the crystals turn whiter and clearer (or maybe the opposite: more opaque) and give the sativa effect. I guess that contradicts the fact that sativa/indica ratios are given based on the strain, not how much longer you allow the buds to mature. Can someone clarify?