Code in Mona Lisa's Eyes:How did Da Vinci put codes so small, you would need hyper-magnification to see it?

If there are really small codes in Mona Lisa's eyes, it would have been possible Leonardo da Vinci inscribed them. As they were trained young and more thoroughly, people back then were much more skilled in handicrafts than we are now. Plus, there were indeed magnifying instruments available. In several 15th/16th century cabinets of curiosities, many objects of miniature size are found, such as a rice grain with a detailed portrait, a cherry stone with a hundred faces and a chess board with chess pieces on the head of a pin. I'm not joking!