El Greco created drawings and small sculptures to serve as models and used them repeatedly in his works, as the faces of the angels and the Virgin clearly show.
His ground evolved from light to dark, and in areas where the paint was applied less heavily the ground layer shows through, lending the surface a violet hue that enhances the sensation of depth. He applied subtle white and crimson highlights to the inner corners of the eyes, which
intensified the gaze and achieved the watery pictorial effect that characterises his style and makes his figures seem so lifelike.
For the flesh areas, he began to use a combination of colours and stains created with glazes beneath which the underdrawing gradually disappeared.
Over time, the faces became increasingly white and luminous, abandoning naturalism in favour of an idealised ethereal beauty.