Grayscale coloring is an out of this world direction of adult coloring for me. It requires a special level of professionalism to show the depth and light using only the gray palette.
Nikki Burnette is the author of 2 volumes of Spellbinding Images: A Grayscale Fantasy Coloring Book available in 2 editions (Beginner’s and Advanced). In this video she has used gel pens coloring over a few grayscale image from her books. Gel pens are not a usual decision when choosing a material for grayscale coloring, and a professional like Nikki did an amazing job using Art-n-Fly Gel Pens and Uni-Ball Signo White Gel Pen on her book.
In case you liked the images, feel free to purchase her books using the links below.