Crystal Violet, Gentian Violet, Methyl Violet 10B

Crystal violet or Gentian violet (also known as Methyl Violet 10B, hexamethyl pararosaniline chloride, or pyoctanin(e)) is a triarylmethane dye. The dye is used as a histological stain and in Gram's method of classifying bacteria. Crystal violet has antibacterial, antifungal, and anthelmintic properties and was formerly important as a topical antiseptic. 

The name "gentian violet" was originally used for a mixture of methyl pararosaniline dyes (methyl violet) but is now often considered a synonym for crystal violet. The name refers to its colour, being like that of the petals of a gentian flower; it is not made from gentians or from violets.