How to manufacture cultured stone?

Question:I've been making cultured stone. I have some nice molds. I use portland and perlite and I dye the mix with iron oxide pigments. I can make really nice stones of a uniform color, but when I try to put other colors in it doesn't look right. I tried sprinkling the dry powder in the mold first before I pour it. I have tried to spray the pigment in (mixed with water), I have tried a paint brush, I have tried to mix the colors with concrete and then paint them on to the mold. Nothing looks "real". I am getting frustrated. Someone told me I may need a vibrating table to "work" the color in when I sprinkle the pigment into the mold but that is the only suggestion I have gotten. I think a vibrating table would help me get rid of the airholes on the face of the stone but my problem is the coloring, not holes. Any help in this matter would be greatly appreciated. I have looked for videos, books, etc. with no luck. If anyone has experience with manufacturing cultured stone please help.

Answers:
I install man made stone and I have seen or I have been to places where I buy it and I have wacthed the workers make it. Just cause I thinks its interesting. I seen a worker use a huge shifter, its like a cup with a handle and a lever in the handle where they grip it with there hand. And he sprays it with the shifter. The actually name (shifter) I do not know if this is right. But it looks like a huge shifter like a baker uses to dispense flour on a baking sheet. And it worked the same way. The lever when pulled spins inside and sprays the flour like a powder in the air and it falls evenly all over the surface.