Again use the circle selection tool. Copy this selection. At this point you could just paste to a new image, etc. I opened up a 100 x 100 pixel background the same as the one on this page. I then pasted the selection from Step 3 as a new layer, and added a drop shadow.
Results are at right.
This resizes just the pearl. Results shown at right. Pretty nice looking pearl without PS or a sphere designer plug-in. I then began to adjust the radius and the height to obtain my own setting as seen in Step 2. From there I proceeded through the other steps to get the end result seen above.