How to Color The Cracks On My Black iPhone?

My iPhone cracked recently. Even though that is usually a bad thing, I'm still looking forward to coloring in the cracks. Other websites say they use highlighters, sharpies, and I've tried them all. But there's one problem: I own a black iPhone. I've tried changing where my iPhone is from ( making it a white iPhone ), but that doesn't seem to help. Nothing shows up, and I've seen pictures of colored black iPhones online, but I can't seem to find a way to do it.

Black nail polish?

I used food coloring. But I have a white iPhone so I don't know. You can try nail polish or gold & silver sharpies that would be really cute <3