Need Some Pointers To Use My New Led Light Properly.

Looks like the lights are too "low". Try bringing them up to a higher angle and see if you like the results.

I try to make the angle as close to 90-deg as possible before either getting direct reflection off the coin or slab surface into the lens or interfering with the shot by getting in the way. You can see the shadow of the light in many of my shots where it is just inside the field of view. This is mostly for color. It also has the effect of creating shadows around the main devices that help emphasize design elements. Low lighting angles create bright halos around the elements due to reflections off the edges of the elements.

The principle you need to know for luster is that you never want to have opposing lights. Luster is created by direct reflection to the lens from "luster mirrors" on the coin surface. Since the surface is rough, the high spots on each tiny rough area reflect light directly to the lens. What we call luster is due to contrast between the bright luster mirrors and the local dark areas that reflect light away from the lens. If you shine a light from the opposite side of the coin, you will illuminate a second set of luster mirrors in areas that would have been dark from the first light, killing the local contrast and thus the luster.

Another principle for luster is that it is excited in a line perpendicular to the incident light direction. If you could truly get the light at 90-deg, the light is uni-directional and you would get no luster because the reflections are uniform over the surface. As you lower the light angle from 90-deg, luster will "pop" nicely at 10-20deg off vertical, then will be gone again at 10-20deg off horizontal. Best luster happens somewhere in the middle, but for other reasons (color, shadow detail, etc) it's best to make the angle on the high side rather than low side.

A dramatic way to show luster on cartwheel coins is to place the light at 10:30 and 13:30 (or 4:30/7:30, 12:00/15:00, etc). These are 90-deg apart and will excite an X pattern in the fields. But as long as you come in at non-opposing angles you will be fine. Each coin may require different lighting heights and angles to maximize the effects you're looking for. Experiment.