Conversation so far:
what is the mystery behind mona lisa painting
One long-standing mystery of the painting is why Mona Lisa features very faint eyebrows and apparently does not have any eyelashes.
was the mona lisa eyebrown and eyelash mystery solved?
Pascal Cotte, a French engineer and inventor, says he discovered with a high-definition camera that Leonardo da Vinci originally did paint eyebrows and eyelashes on The Mona Lisa.

Question: how was the mystery solved?
Self-contained rewrite: how was the mona lisa eyebrown and eyelash mystery solved?