Diego is a young man of below-average height and slim to medium build. He has light hair, dark eyebrows, and light, sharp eyes. He commonly wears an equestrian helmet with the letters "DIO" loosely mounted on bending pins emerging from a small ribbon tied at its front, a turtleneck jumper patterned with a diagonal grid, light, mid-forearm-length gloves, jodhpurs with flared hips, and tall, dark riding boots.