Just let me get scientific for a momment. Ther are too types of muscle tone, 1. myogenic - which is what your muscles look like at rest. Either look 'soft' or 'dense' ie ripped. 2 Neurogenic- What you muscles look like when they are moving, like when your are flexing in front of the mirror.
So, to develop these two types of muscle tone, doing high reps with low weights so you can feel the burn is OUT. There is no science or reasearch behind that theory. Heavier weights and lower reptitions are IN.
Next time you are training, crank out a few sets of 7 reps with a heavier weight than usual. Your body and muscles will thank you