Gentian violet may be a strong staining agent, but it can be treated. The best strategy is treat the stain quickly by soaking it in cold water and pretreating it with a pre-soak product. However, if you cannot get to the stain quickly, or if the stain is on skin instead of clothing, other stain-removal methods are available.
Soak a portion of a cloth with the alcohol. Dab the stain with the cloth, allowing the alcohol to soak up the violet.
Dab at the stain until it begins to lift.
Wash the stained area with warm water and a mild soap. If the stain hasn't completely dissolved, repeat steps 1 and 2.
In place of alcohol, try vodka to remove the violet stain. For fabric, also try to spray hairspray onto the stain before washing regularly.