Any reef-save pigments for man-made reefrock?

[LouisianaReefer]

I am wondering if there is any reef-save pigments for man-made reefrock. I have been making my own reef-rock for a year yet would like to find out about how to add pigments to the concrete mix.

 

[Reef Frog]

Just an idea: Find a colored concrete additive you like at the home store and get the list of ingredients & chemicals. Then maybe the folks in the chemistry forum can give you some useful information if you post them there. Or there may be info in the DIY forum.

I've seen it used for concrete sidewalks & patios & it looks nice in that application. But the uniform color might look unnatural for LR. In a few years down the road with the rocks covered with corals, mulm etc, the color might not matter much.