3D button with highlights, a nice "gleamie" highlight with the effect of a raised edge and a concave surface. Here is how to create it in Illustrator, and it is quite simple to do!
Start with a circle, hold SHIFT to make it a perfect circle. Apply a linear gradient to the shape
Open the Gradient panel under the Window menu. Set the right color stop to a SOLID color, set the left color stop to the same color and set the opacity of the left color stop to 20%
Duplicate the first circle, rotate it 180° and align it with the center of the original circle.
Edit the gradient so the color fades to white.
Set the gradient of the 2nd circle to fade from the original blue to white at the other end and set the white at 60% opacity.
Draw a large oval and rotate the oval at about a 30° angle. Fill the shape with white and position it over the shapes a bit off center.
Set the white oval to 65% opacity.
Duplicate the oval and make it smaller and place it over the upper edge of the first oval.
Select both ovals then use the pathfinder to Minus the Front object.
Copy the first circle and then choose Paste In Front. You want the original circle to be in front of everything. I added a red stroke just to see the shape, the stroke disappears when we use the shape as a clipping mask.
Now the highlight is clipped to the original shape of the circle.
Draw an arc using the Arc tool. Make it a white stroke.
From the Stroke Panel, make the stroke 20 pts wide and apply round end caps on the line.
Use the Width Shape Tool to select the end of the arc, then pull a bit to widen the end of the arc.
Add an 8 pt white stroke to the inside circle.
Open the Appearance Panel from the Window Menu. Select the Stroke portion in the Appearance Panel.
Go the Effect Menu and go to the lower section (Photoshop Effects area) and choose Blur>Gaussian Blur. Sect the blur to 10 pixels.
Select the the arc. In the Appearance Panel choose the stroke. Go the Effect Menu and go to the lower section (Photoshop Effects area) and choose Blur>Gaussian Blur. Set the blur to 35 pixels. Set the fill opacity of the stroke to be 90%.
Here is the final button. Looks 3D with a nice highlight and a "gleamie" arc cast on the edge.