Gregory Grefenstette learned oil painting under Elise Chaigneau, copying the classics by Chassériau, Waterhouse, Alma-Tadema, Freud, Ramon Casas, Bonnard, and Henner, among others.

Later, he devoted himself to portraiture, creating over 45 portraits of people he knows. He cherishes that magical moment when the subject reveals themselves during the act of painting. You have to believe in it at first, and then it happens.

More recently, after an in-depth study of color under the guidance of Sylvie Guezennec, he has been seeking brilliance and dynamism in his paintings.