Yes, you can use sharpies magic markers on rhinestones and other glass flat top beadwork. It goes through the wash just fine. Be sure to color the sides of the rhinestone if it is not sewn on yet. Don’t risk touching the fabric by trying to color the edges if the rhinestone is already stitched onto the dress. The coloring the top will be fine.
“Mirror” or “broken glass” dresses covered in large flat rhinestones can be turned into a stained glass work of art using sharpies.
This is also a great trick if you are having a hard time matching beadwork that needs to be repaired or replaced. Find the right shape in a silver rhinestone and color it the correct color you need to replace missing beadwork.
My pageant girl colors her costume jewelry. Of course, never do this to expensive jewelry, but when the color is more important than anything, getting some cheap jewelry in silver and then turning it into a specific color can save a lot of money, time and grief.
Incorporating color into a wedding dress that already has rhinestone beadwork on it can be fast and easy.
I hope this opens up a whole new world of ideas for you and your beadwork creativity.