Answer:
Always wax, yet always wane: I melt, succumbed to the flame. Lighting darkness, with fate unblest, I soon devolve to shapeless mess.
I'm sometimes white and always wrong. I can break a heart and hurt the strong. I can build love or tear it down. I can make a smile or bring a frown.
A precious stone, as clear as diamond. Seek it out while the sun's near the horizon. Though you can walk on water with its power, try to keep it, and it'll vanish in an hour.
You heart it speak, for it has a hard tongue. But it cannot breathe, for it has not a lung.
In the night a mountain, in the morning a meadow.
Iām grown from darkness but shine with a pale light. Very round I am and always a lady's delight.