The pen-ultimate pencil is here! Brenda Christian’s Brow Definer Pencil Pencil is a neutral ash based color which reacts to the ph of your skin in the eyebrow area. This pencil becomes warm or cool, light or dark depending on the ph of your skin. Brow Definer is suitable for all skin and hair colors from Swedish Blonde (ja!) to African American Ebony (that’s right!). Brow Definer never looks ashy because it goes with your own natural coloring.