1. Create a solid color circle.
2. Create a white shadow with the Inner Shadow blending option from the Layers Palette.
3. Use Gradient Fill in Blending Options to darken the side opposite of the white shadow.
4. Create a new layer and use the Brush tool to create a reflection near the center. Use a large, soft brush with medium to high opacity.
5. Do the same as in step 4 but with a smaller brush size, and hardness near 100%.
6. Create a new layer. Use the Gradient Fill tool with the Radient fill button selected to make the shadow for the ball.
7. Flatten the shadow using the Free Transform tool.
8. Move the shadow behind the ball.
9. Lower the opacity of each to around 50 percent. You can also keep the opcaity of the sphere at 100% and just pick 'Overlay' in the dropdown box of the Layers Palette. This will give it a different look other than just lowering the opacity. It depends on the background you put the sphere on (step 11) to determine what it will look like. You can try both to see which looks best.
10. Use the Liquify tool to adjust the shadow.
11. Drag the ball and shadow layers onto the photo.
12. Use the Liquify tool to warp the background behind the ball. Or, you can select the sphere with a select tool and then click on the layer of the background (in this case the field). Then select Filter> Distort> Spherize. It will spherize the background in the same place the sphere is at to give the illusion of looking through glass. Before you do this you must have the sphere in the place you are going to keep it.
13. Use the Smudge tool to adjust the shadow and soften the edges.
14. Adjust the lighting/shadows/opacity to make it look more realistic.
15. After a bit of tweaking (and switching to the 'Overlay' option described in step 9).
