Analysis of information sources in references of the Wikipedia article "โมนาลิซา" in Thai language version.
It is actually quite dirty, partly due to age and partly to the darkening of a varnish applied in the sixteenth century.
The original Mona Lisa in the Louvre is difficult to see—it's covered with layers of varnish, which has darkened over the decades and the centuries, and even cracked', Bailey says
time has aged and darkened her complexion.
