|When a spot light is used in this situation (under the mineral) it is possible to create a images reminiscent of those created using the Jeffrey Scovil set up.
Note: high quality dual color gradient backgrounds are relatively expensive. By using the background offset a few inches behind the mineral sample you can create low resolution backgrounds on any ink-jet printer that will be further blended by the limited depth of field and look very good.
You can also create radial color background, or even mimic the effect created by the Scovil under spot light on a single color. Simply create a gradient that runs from one hue (say dark blue) to a lighter (or darker) shade of blue. You could even create custom shaped gradients like stars, pentagons, etc. Your imagination is the limit.