The ruling on water not reaching under a ring or watch during wudu'

Question:
May Allah reward you, Honorable Shaykh. This questioner says: If it is not obligatory to move the ring, and likewise the watch, what is the ruling if the water does not reach what is underneath them?

Answer:
If you know that the water did not reach what is underneath them, wash it; wash what is underneath them. But if you did not know, and you completed the water over them and it flowed, then wash, yes. And if you did not know that it fell short of what is underneath, the default is that it was completed, yes.