I am into all the technical details how to produce dials. But as a main approach you apply diffetent specific colored lacquer on the surface (called „sapon“). It takes many trials to find the right colors. Then you apply the different decorations on the respective colors/ parts of the dial (eg Sunray finish on the main part, circular graining on the outer minuterie, „azuree“ (small concentric circles) on the Chrono counters, etc...).
One that is done you stamp the numbers and hand apply the indexes on the dial....