Well, once you dab it on, (DON'T RUB! IT WON'T WORK :) ) then dab until it blends with your skin, one cannot tell its there. So it would not be obvious under foundation. I haven't ever worn foundation and I love how this evens my complexion completely without looking like make-up. Thank you for your question!
Oddly enough, its green. Lol but THAT is what helps it blend to any skin color. Just remember DAB! :) the first time I tried MINE I tried to rub it in. woah! Dabbing works.