Few colors say focus like a deep green, and a study is the natural place to use it. Deep forest on the walls wraps the room in a rich, grounded tone that feels like an old library — serious without being severe, and far easier to live with than black or charcoal alone.
A warm white runs along the trim, ceiling, and casings to keep a crisp edge around all that depth, stopping the green from feeling like it is closing in. Charcoal carries through on shelving or a desk, sitting close enough to the green to feel layered rather than busy. The warmth comes from soft tan — through wood, a leather chair, or a worn rug — which echoes the natural side of the green and ties everything together. Keep the green dominant, the white sharp, and the tan warm, and the study feels both handsome and easy to work in.