Infrared Scan
In 2004 experts from the National Research Council of Canada conducted a three-dimensional infrared scan. Because of the aging of the varnish on the painting it is difficult to discern details. Data from the scan and infrared were used by Bruno Mottin of the French Museums' "Center for Research and Restoration" to argue that the transparent gauze veil worn by the sitter is a guarnello, typically used by women while pregnant or just after giving birth. A similar guarnello was painted by Sandro Botticelli in his Portrait of Smeralda Brandini (c. 1470/1475), depicting a pregnant woman on display in the Victoria and Albert Museum in London. Furthermore, this reflectography revealed that Mona Lisa's hair is not loosely hanging down, but seems attached at the back of the head to a bonnet or pinned back into a chignon and covered with a veil, bordered with a sombre rolled hem. In the 16th century, hair hanging loosely down on the shoulders was the customary style of unmarried young women or prostitutes. This apparent contradiction with her status as a married woman has now been resolved.
Researchers also used the data to reveal details about the technique used and to predict that the painting will degrade very little if current conservation techniques are continued. During 2006, Mona Lisa underwent a major scientific observation that proved through infrared cameras she was originally wearing a bonnet and clutching her chair, something that da Vinci decided to change as an afterthought.
Read more about this topic: Speculation About Mona Lisa