The water effect is nice. Im sorry the rest is imo completely wrong. Shading, shape, style ..

The shading of a gemstone is high in contrast and angular in shape.  The water is very good, but the clouds are lacking.  I think the world would look dreary if the water levels rose that high, wouldn't you?  The clouds don't seem to send that message.

 The water looks good but the sky and the rock could use work. The outlines on the rock are really obvious and not very attractive, and the shading is poor.

Not enough minerals

lol

very nice picture!

The water shading is very nice.

Thanks, it was a bit rushed in the end so yeah, clouds need some more love :( Was last second decision to add them as the piece was missing some sense of scale without them. Glad you liked it in spite of the flaws :)

 The water is pretty nice. I would use another green though.

 Awesome! I know there isn't much time left for editing before the challenge closes, but I'd suggest cleaning up the clouds if anything.