A contradiction in terms?
Brian Beyer has kindly put together an article on Darkfield Illumination for the upcoming issue of the Monthly Mineral Chronicles.
Darkfield Illumination is a technique that can be used to photograph the interior of crystals, to capture inclusions, internal fractures, and other things. It produces a better result than incident (lit from above) lighting, or transmitted (lit from below) lighting.
Brian’s article explains how to build your own Darkfield Illumination mechanism. I used his example, but instead of using the materials he described (as I didn’t have any to hand), I built mine out of black card.
This photo is the first attempt and I need to experiment a bit with the lighting. It is the interior of a pink tourmaline crystal from Kunar, Afghanistan. Photo width is 2.5mm.