Wow...triple post! Anyway, Here is what I think of each image:
First: Really, really awesome! Love the gold used in the background.
Second: Nice, but the top of the device looks wierd, do not know exactly why. Otherwise, another great image!
Third: Like the texture used, but the shadow is pixelated on the bottom, and the top right of the stone is also pixelated. Worst of the three. (No offense, of course)
I hope I helped, and you are really improving!