Removing a Chalk Stain on Silk?

I used pink chalk on my hair when I wore a Cheongsam (Chinese silk outfit) and now it is stained. I thought chalk would be easy to take off with a normal detergent. But my mom told me that stains on silk will be hard to remove. And that was true, the stain didn't washed off after I washed it.

Does anyone know how to clean it without ruining the silk?