Exhibit & window display designers use light-selection as the primary tool to enhance objects on display.
Some typically available lighting options include diffuse overhead panels, back-lighting light boxes, linear fluorescent tubes, compact fluorescent bulbs, incandescent bulbs, halogens bulbs, LED light strips and bulbs.
One main concern is the size of the light source. If a mineral is illuminated with a broad, diffuse panel it will appear dead and lifeless. If the same crystallized specimen is displayed under several small point sources of light it will sparkle and come to life. LED light strips are particularly good at providing these small, multiple point sources of light.
Each point source creates a reflection. The more points of light, the more sparkles. Of course there is a practical limit. Too many point sources will start to merge and have the reverse effect.
The effect of point sources of light can be seen in every jewelry store. Look at the store’s lighting. In the ceiling will be an array of small point sources of light, generally halogen or LED lights. Each light source will reflect and refract off the gemstones and give it that brilliance that we love from gems. To see the difference, take a diamond from the store outside to a shaded area. Now the light will be coming from the diffuse light of open sky and will look dead.
The same effect is used by mineral photographers. A good photograph will carefully illuminate the crystal faces so that each face is differentiated from adjacent faces. To do this, several light sources and small reflectors will be used. See Jeff Scovil’s excellent book on mineral photography to see what a finished setup looks like – very elaborate. Most times photographers will not use the standard photographer’s tools of reflecting umbrellas or broad diffusers because these have the effect we discussed, of dulling the mineral and not describing all of the faces.
Objects in your display case can be viewed from many eye levels and vantage points. The display case allows something that a photograph never can – you can pick up your specimens and move them underneath the case lights. The lighting therefore should be optimized for general viewing and for the handling of the specimens.
Interestingly minerals which do not have well-defined crystal faces, like botryoidal or reniform masses (hematite, prehnite, smithsonite), look better under diffuse illumination. Many translucent or transparent minerals (agate slabs, ametrine crystals) look better when “back-lit”. It is often advantageous to display these mineral types separately under the optimum lighting conditions for them.