inclusions, photomicrography, gems

A. de Goutière introduces gemstone inclusion photomicrography through a practical account of equipment, lighting, film handling, and specimen preparation, illustrated with three examples of his own work. Addressing gemologists who may be discouraged by perceived technical difficulty or cost, he explains that a good binocular microscope, a single-lens reflex camera with automatic exposure, and a suitable connecting adapter provide the basic means to begin. Inspired by E. Gübelin’s Internal World of Gemstones, the author adopted a Wetzlar trinocular microscope mounted on an Eichhorst Gemmaster base, allowing an Olympus OM-2 camera to remain attached and ready for use. He identifies the camera’s compact construction, low weight, and off-the-film metering as useful features, with automatic exposure determination freeing attention for composition and focusing. His preferred photographic material is Ektachrome 160 tungsten professional film, prepared in ten-exposure cassettes to shorten the interval between taking photographs and reviewing results and to reduce waste when a partly exposed roll requires immediate processing. Unexposed film is stored under refrigeration. Lighting receives particular emphasis: de Goutière considers fiber-optic pinpoint illumination essential for this work and describes using as many as three light guides together with transmitted illumination. He stresses the need to arrange the lighting carefully, compose the image deliberately, and keep specimens completely clean, since even a small particle of dust can spoil a photograph. The illustrations demonstrate different subjects and combinations of illumination. A thin liquid-film inclusion in colorless Mexican topaz is photographed at 17× using oblique illumination. An insect trapped with a flower in Dominican amber, notable for its bright red eye, is shown at 8× with partially polarized transmitted light combined with oblique illumination. A goethite cluster in amethyst, compared visually with an Apollo spacecraft and bearing a small red crystal on its blunt end, is recorded at 14× using oblique and transmitted illumination. The article recommends the Photoatlas of Inclusions in Gemstones by E.J. Gübelin and J.I. Koivula and lists further reading on microscope photography, inclusion photography, and controllable pinpoint lighting. It presents an accessible starting method grounded in the author’s working practice rather than an exhaustive technical treatment.