Technical Evidence For Raphael
The pounce-marks around the fingers of the Madonna's right hand could be evidence of the Tondo being a copy, insofar as the outlines of the Sistine Madonna may have been traced on to paper, then pricked and pounced on to the support.
However it would appear that the pouncing only occurs in the area of the Madonna's right hand, which would point to the use of an auxiliary cartoon.
"Drawings of this kind represent the very last stage of the preparatory process. They belong to a category that Fischel was the first to identify, to which he gave the name 'auxiliary cartoon'...Fischel convincingly explained them as studies worked up from outlines traced through from the full-scale cartoon, of details that Raphael wanted to realise as carefully as possible before embarking on the painting itself. This practice seems to have been peculiar to him, and is further evidence of his painstaking method. "314
Gere and Turner also point out that Raphael's auxiliary cartoons are usually of heads or hands.
Strikingly similar pounce-marks are found in the reflectograms of the Madonna del Granduca and the Madonna in the Meadow: in the first the pouncing follows the outlines of the Child's fingers and toes, and in the second it follows the outlines of the toes of both the Madonna and the Child.
The evidence of the pounce-marks in the Tondo suggests that the hands were studied closely with the use of an auxiliary cartoon, and this would further suggest, following Gere and Turner's opinion that the use of the auxiliary cartoon was "peculiar" to Raphael, that the author was Raphael or one of his studio.
||Laurie, A.P. : The Painter's Methods and Materials : Dover 1967 : p.90