Darken stretch marks?

It's not going to work. If you darken them with spray tan (for example), they'll stand out more.

I don't know what you mean by wanting to darken stretchmarks. But I do know of ways to fade them out. I'm older. Have had two (now grown) babies. I've gained and lost weight through the years. Late 40's. I have been lucky, I've seen so much worse when it comes to stretchmarks. But, I've always sworn by cocoa butter. I get the one that has no fragrance in it, because it can definitely clash with your perfume. The efficacy of cocoa butter in my opinion, is tried and true for me. It reduces the appearance. But I would never want to darken them?

I mean darken them to my skin color or fade them. I'll try coco butter.

Yeah I use Palmers Coco butter skin therapy oil. It takes a while for it to be effective but I've heard good things