Method and apparatus for producing textile yarns so that one surface of the yarn exhibits a visually perceptive darker color hue when compared to another surface of the yarn. The yarn surfaces are coated with a colorant-containing liquid (e.g. a dye- or pigment-containing liquid) and are subsequently dried to effect a drying rate differential between the one and another surfaces to cause the colorants to migrate towards the faster-drying surface to a degree sufficient to achieve the darker color hue thereon. Twisting of the produced yarns during packaging and/or weaving will thus create a woven textile fabric having randomly distributed color variations to achieve a visually pleasing striated, tone-on-tone or heather fabric appearance.