From anhistorianabouttown.com/mary-queen-of-scots-an-inconvenient-queen/.
The wide wheel ruff and inset showing the decapitation of a woman lead to a conclusion that this is a posthumous propaganda portrait. The surcote may be nothing more than wide strips.
Keywords: Mary Queen of Scots, Mary Stuart, Mary I of Scotland, Stuart family, Scottish, Queen, attifet headdress, veil, fitted bodice, highe enclosing neckline, wide ruff, long under-sleeves, back-flared contasting cuffs, jeweled crucifix, necklace, surcote, elbow length rolled split over-sleeves, close skirt