You need to alter the white balance of the camera to adjust for the different types of light. Trouble is, if you're using two different light sources, like tungsten and fluorescent then you'll get two different colours in the image, which is very difficult/impossible to remove.
Another trick for clear glass. If you place two pieces of black card (hey, a book will do!) quite close to the sides of the object, then this refracts the dark light to show up what can otherwise be very pale edges against a white background. Quite useful when the glass is plain and not cut.