For my mold, I mixed 4 kg of white cement with 1 kg of sand and 2 liters of water. (Usually I mix in 1:1 ratio, but I didn't have more white sand on hand). Stir, stir, stir. Add pigment to the mix—beige worked great for me. If I could redo this, I’d dissolve the pigment in water first. It clumped a bit, but hey, it still turned out fine.