Gradient?s parameters:

Take the next tool
and try to represent a semi ellipse on a white color background:

on the layers we should have

Using
the previous instrument, represent the first elements for the indicator to be:

Blending Options-Bevel and Emboss

Take the next tool
and try to represent a semi ellipse on a white color background: 
on the layers we should have

Using

Blending Options-Bevel and Emboss
