As I recall, you can buy a special filter to get the sunburst effect - but the tiny sparkle below, just above the balance jewel, was completely accidental and no filter was used!
My setup uses three lamps, hence the six-pointer. You'll notice that the angles between the points and the point intensities are not equal because of my unequal lamp placements and distances.
So, how did the sparkle appear? The light from each lamp hits the curved bevel on the regulator and is reflected up into the camera's field of view. Even though the lamps have diffusers on them, the single curvature concentrates the reflected light and gives a fan shaped reflection beam rather than a spot beam. The "accident" occurred due to the exposure setting used. It was enough to saturate the image at the center of the sparkle but to have less and less saturated area going outwards along each reflection beam.