How to bring the color out in native american stone tools?

[EYEROCK]

I never use any chemicals, hard brushes, or anything stupid like that to get the dirt, or years of hardened coal silt that is caked on some of my finds, thanks to years of laying in the Schyukill River. I want them to look like they are wet! Lol

 

[tedcunningham]

Suspect stone artifacts. Anything good All found in minnesota. Lemme know in comments what yall think. Thanks!