It has been called โ€œmiracle water,โ€ but an essence โ€” the beauty product thatโ€™s considered an integral step in Korean and Japanese skin-care routines โ€” is no water.

Nor is it a toner, serum or moisturizer. An amalgam of all of the above, this all-in-one has elicited both praise and skepticism since it entered the United States beauty market from Asia about seven years ago.