First at all, you'll have to complete it, with your own style, cause this tutorial shows you how to do the defaults. At the end of the post, you'll see what i'm talking about. Open a new, transparent img. After this make one circle shape, with gradient tool like this(pick your own colors, but if you want same: 7c7c7c and white): after this don't cancel the select, make a cltr+shift+i, make a new layer, and fill it with black (or other color. depends on your color pick) Filter>Blur>Gaussian Blur (y you can make it with inner shadow, but i prefer this way) Select the orb, ctrl+shift+i again, and clear. Select the place what you want to fill with glass effect, and with white+transparent gradient fill it. and delete everything what is outside from the orb duplicate the orb's layer add noise make it grayscale with Hue & Saturation, and merge the H&S and the Duplicate layer. The "last" step is: Filter>Blur>Motion Blur, ctrl+click to the original layer's thumbnail, ctrl+shift+i, clear.. Now i'm done with the tutorial, now you just have to add your style, and make it better with it, like this:
or this:
if you have questions, PM me. and if my english isn't the best: