Agate is a variegated stone, a conglomerate, and according to it’s cut will sometimes show a number of veins usually circling around some center.
The colors vary in various specimens of agate, some being rather light and others very dark, so you really have a good range to choose from – crimson lake, Prussian blue and chrome yellow or ocher.
Basic White is the background for agate.
The character veins of the marble are formed with a quill feather, in a transparent crimson color.
When this is dry, the work is again covered in the same manner – but with a darker color – touching certain parts with fresh color, which is left un-blended to give a sharp edge.
The character veining is then continued, and a greater variety introduced with a bright medium tone of green, formed by the mixture of blue and yellow.
With a water color brush, dipped in faux glazing liquid, the work is then sprinkled, and all the three colors are introduced again in places with a lining brush so as to heighten the tone and give realistic effect to the faux marble.
Marble Veining Feathers

