Highlight black hair without Bleach??!?

Hi so I was at school today and saw this girl with GORGEOUS hair. It was black from afar but when u got closer it had a subtle maroon color to it. It wasn't so little that u couldn't see it. but it wasn't totally noticeable either. It looked like she highlighted her hair maroon without bleaching it but I'm not sure. So how would it look like to get black hair highlighted with maroon/burgundy highlights w/o bleach? thanks!