I was surfing in 470000 Russian thesis database and I found an research on laser oxidation of metals for obtaining color patterns. I returned to Google and found above stainless steel piece made by Singapore researchers with nd yag lasers. Mechanism : Heat causes an chromium oxide layer at bottom and iron oxide layer on top of the first and different heats increase the iron oxide layers and change the color.Similar mechanisms apply on glass.
I found electricity is used to create automobile point welds and same technology could be used to create controlled heat and controlled color large pixels to form an lower resolution color print on stainless steel or glass. If I am not wrong , as we see at dish washing machines , if we ground the piece , no danger.
Is there a simpler , chemical way ?
Mustafa Umut Sarac