Prepare the surface by painting the base coat and colors. To get the color variations, apply dark glaze with fabric or plastic over a light base coat.
Outline dark veins using a feather. Dip the feather into the darkest shade of glaze, shake off the excess paint, and use the tip to outline the darkest sections of the base coat. Draw the veins up and out from darker to lighter areas. Tilt the feather as you paint to make wider sections of dark color.
Draw a soft dry brush across the wet paint to feather the color out and create an illusion of layering. Leave some veins well defined, as surface veins naturally appear. Draw the color out further from others to create subtle shading.
Prepare the surface by painting the base coat and colors. Create the color variations with dark glaze over a light base coat. Keep in mind that you will be creating the veins with the light base coat.
Use the light base coat color to create light veins. Light veins are more dramatic as the darker colors do not allow the lighter shades to gently merge into subtle color tones the way the translucent lighter colors allow the darker veins to blend into view.
Feather with the dry brush, but do not draw the color out as far as with the darker veins. In natural stone, the darker color does not allow the depth and variations of color that usually occurs when the darker veins are viewed through the lighter translucent tones.