This is Photoshop tutorial for beginners of creating simple glassy Mac OS X related ball
1. First we must create circle with gradient. It must be complex, of minimum 3 color points.
Select Ellipse Tool and holding down Shift draw circle
In Layers window press Add A Layer Style and select Gradient Overlay
Click on gradient to edit it
Create few points with colors similar to this 
2. We put our ball on white surface, so it must be shined by environment.
Add A Layer Style -> Inner Glow
3. Creating main light reflection. If our ball is made from glass, it must reflect source of light without blur and reflection must have clear border. Like it is in Mac OS X interace and some icons.
Create Ellipse
In Layers window press Add A Layer Mask
Select Mask by clicking on Layer Mask Thumbnail (in Tools window Background and Foreground colors will change on black and white, because mask can be only in grayscale mode. More black – more transparency)
Select Gradient Tool
Choose Radial Gradient
Drag over the shape to create gradient mask. Remember that borders must be visible, so you must drag mouse next it.
4. Shadow. To create shadow we will use also shape with radial gradient.
Create circle (shadow must be of ball’s color, because it is transparent)
Add Mask
Create radial gradient mask like this
Deselect mask by clicking on Vector Mask Thumbnail
Transform it to make something like this (Cmd+T)
5. Creating caustic.
Duplicate layer
Change its color on light-yellow
Transform to make it much smaller
6. To Make our ball much realistic, we must add reflection of white surface.
Duplicate first circle
Right mouse button on layer -> Clear Layer Style
Double click on Layer Thumbnail
Change color to white
Select Vector Mask Thumbnail
Draw one more ellipse holding Alt to make new shape Subtractive
Add Layer Mask
Make radial gradient in layer mask
教程来源：http://www.icondrawer.com/main.php