To start, you can grab the image that you wish to apply the diamond to. It must be a darker image. I used this watch that I made earlier. Next, download the PSD shape of the diamond here. Once opened drag the layer titled, "Diamond" to the canvas that bares your image, and place where you want it.
Now that you have your diamond shape, you can now right click on the "diamond" layer and select, "Blending Options...". Now click on "Outer Glow".
Do not click OK yet... still more to do
Now click "Bevel and Emboss".
Do not click OK yet... still more to do
Now adjust the graph to match image below, then click ok
Now click "Contour".
Do not click OK yet... still more to do
Now again, adjust the graph to match image below, then click ok
Now "Color Overlay ".
You may now click OK.
The Results!!!
More Tutorials: 
