Answer:
A precious stone, as clear as diamond. Seek it out whilst the sun's near the horizon. Though you can walk on water with its power, Try to keep it, and it'll vanish within an hour.
What is weightless but it needs two person to hold it?
I sleep by day, I fly by night. I have no feathers to aid my flight.
I have four wings but cannot fly. I never laugh and never cry. On the same spot always found, toiling away with little sound.
Talks like this, a green wise man does. Guess my clue, you will.
What is always coming but never arrives?