What paint do for the nails of a Phicen fig?

[WolfElite]

Just recently purchased a Phicen Seamless Female Jiaou Doll and putting together my own Black Widow fig. And I would like to know what proper paint I should use for the nails of a Phicen fig?
Can I just use like a black Sharpie ultra fine pen to paint the tips of the hands?

 

[Pro Design]

acrylics should work as there shouldn't be much rub or scuffing of that small area.

i'd also grab a tooth pick and take a razor blade and shave off one end to get a nice long needle point to it... then use that tiny tip to do the fine detailing under magnification.