To provide a process for the coloring of colored crushed stones for constructing a mosaic garden having varied color tones resistant to fading over a long period without degrading the graceful appearance of natural stone.

Crushed stones of igneous rock, sedimentary rock or metamorphic rock are washed and dried and the obtained crushed natural stones free from surface impurities are colored by mixing with a two-pack polyurethane coating material composed of a urethane resin prepolymer and a catalyst. A coloring solution composed of the two-pack polyurethane coating material containing the main agent and the curing agent at a weight ratio of 9:1 to 7:3 is mixed with a solvent at a weight ratio of 4:6 to 2:8, a resin-based coloring agent is added to the mixture, and the product is charged together with the natural crushed stone into a stirring mixer, stirred for a prescribed period and dropped on a mesh plate having a relatively large mesh size. The excess liquid is dripped off to effect the application of the color coating film on the surface of the natural crushed stone.