Adobe Bridge Icon
10. Gradient
Use the Gradient Tool and apply a 3 colors gradient as shown (color 1 = k0, color 2 = k16, color 3 = k13).
11. Add New Stroke
To make an inner glow effect, we need to add a new stroke. in the Appearance palette (top right corner dropdown menu), select Add New Stroke.
Align Stroke Inside
In the Appearance palette, selct the new added stroke, fill it with 4pt white stroke color. Then open the Stroke palette, and click on Align Stroke to Inside.
12. White background
Notice when you place the sea shell on top of the icon base, the sea shell is see-through because the blending mode has been set to multiply? We can get rid of that by adding a white background to the sea shell. First copy the entire sea shell to clipboard, then merge the current sea shell by Alt-click on Add to shape area (Pathfinder palette).
Then, Ctrl+F to paste the copied sea shell in front.
Final
The image on the left is my version and the image on the right is the original version.
