This created by creating two colors that both were dark enough to appear black but have a hue that includes the purple and red colors shown above. A circle is created with a stroke of about a quarter inch. That stroke is expanded to be it’s own object then the path is offset . The path is then offset and the created object is changed to black. The blend tool is then used to blend those two objects followed by changing the layer style to “Color Dodge”. The color can then be changed by changing those global colors. An example is below.

The smaller objects pulling away from the circle are created with the circle tool, changing the color to a black and white radial gradient and then changing the blend mode to “Color Dodge”.

Those circles affect the larger ring because they are set to color dodge and can create some interesting changes to the larger circle depending on placement.