All of the following were taken against a mid-to-dark grey background.
With flash.
Modern Venetian-style goblet vase.
Side lit with a distant spot lamp.
Floral engraved water jug.
With flash.
Reference photo of old (and one not so old) drinking glasses.
When using flash, several factors need to be considered, such as:
a) How strong is the flash? Try a layer or two of tracing paper over the bulb to get a diffused light.
b) Is the item decorated with engraving? Experiment with camera distance and flash diffusion to get a better effect.
c) Do other light sources (interior or daylight) still reflect in the item and distract from the detail? Close all curtains / switch off other lights. But this method may require an assistant! If the camera does not allow manual focus by some means, then use pre-focus (hold shutter release button half way) and get a friend to get rid of the extra light sources.
If flash always gives poor results, go for natural daylight but from a distance that provides a soft light, not a bright sunlight glare.
But basically ... experiment. Different items need different lighting to bring out the best, or at least a reasonable, image.
