Etched glass can be one of the more challenging products for a photographer to capture. In addition to dealing with reflections as with typical glass photography, the photographer must also light his subject in such a way as to highlight the etching on the surface of the glass. As with most product photography, using tools designed for this specific purpose will yield the best results. However, amateurs will also be able to photograph etched glass with similar techniques.
Opaque colored glass often photographs best against a white backdrop. However, as most etched glass is pale or translucent, the photographer should opt for a darker background. Black matte fabrics or paper works best as a background as it will not cause any reflections that distract from the glass itself. Because you will be using a black background, you should plan to underexpose your image between 2/3 of a stop and one full stop of light. This means closing your aperture one stop (i.e. from f/4 to f/5.6) or nearly doubling your shutter speed (i.e. from 1/200th of a second to somewhere between 1/320th and 1/400th of a second) beyond what your on-camera meter suggests.
Etching appears more vibrant and more detailed when the light appears to come from within the glass itself. To accomplish this effect, a light panel or light box--a flat surface with fluorescent lighting tubes inside--works best. Cut a hole slightly smaller than the base of the glass in the backdrop. Place the backdrop over the light panel and carefully align the glass over the hole. The hole will allow light to come from the light box into the glass without any additional spillover light. Do not use any other external light or on-camera flash as it will overwhelm the light form your light panel. If you do not have access to a light panel, a standard light or flash unit can be used if the light is funneled and reflected through the hole in the backdrop. Place the backdrop over a sheet of glass--such as one found in a glass coffee table--and place the lamp or flash unit under the glass panel pointed upward.
Every piece of etched glass is different and will react to light in different ways. Experiment by increasing or shrinking the size of the hole in your backdrop, adjusting the angle of the product in relation to the light source and adjusting your camera's angle to the product. Depending on the type of etching, you could also experiment with colored light for a more dramatic effect. A colored lighting gel under your backdrop below the hole will tint the light and produce very different results. Any gel used will reduce the amount of available light, so you may need to increase the intensity of your light source or adjust your exposure settings to compensate.