my roommate claims that she had purple stretch marks too.. really bad ones when she was a teen. SHe's extremely fair. She didnt get any treatments and now her stretch marks are not even slightly noticeable. Im not sure about her, but if you tan, you'll have trouble looking at the area.
The oil is very sticky, but its good stuff!! I would use it at night if ur not using any treatments during nighttime.
So far my progress on the microdermabrasian and chemical peel on the back of my leg has been good so far. Hardly any stretchmarks left, its not as deep and a lot has faded. I just need a few more sessions and im probably stretch mark free.
However, im doing the same treatment on my love handles and so far, one treatment hasn't worked at all. The skin hasn't peeled yet, but it doesn't have the same effect as on my legs. I just think its because the skin there is much thicker and requires more microdermabrasian...ie more scrubbing. Therefore if you use this method, Im pretty sure your results may vary from mine depending on where you do it.
Back of your knees is sensitive skin and its thin there.