First from Charles Sweigart

My opinion on having a color gradient background, especially with transparent and translucent glass, is that the background color will be visible thru the subject and so will influence or alter the actual color of the subject. I think that a plain white, properly exposed and color corrected to pure white, should be the best background choice to represent the true color of translucent and transparent glass.

Placement of lights, intensity, and type of light source will also influence the camera’s capture of the color or lack of color. The reflective surface of glass, especially the glossy polished examples, means that the surface will act like a mirror, even on colorless pieces, and will as such pick up colors from the reflective surroundings.

This means that even the color of a photographer’s shirt can influence the color of a reflective surface.
I think the graduated color backgrounds could be useful to illustrate glass in an artistic sense, especially with the use of complimentary color combinations, but should be avoided if the purpose is to illustrate actual color values of a particular piece.

Achieving graduated colored backgrounds can also be accomplished on a single colored background thru the proper positioning of lighting and the use of colored gels, [a whole other subject].

Next, from Gwen Stebbins on Thunder Gray

Regarding the background color, at Plantation Galleries we used Thunder Gray to photograph our glass. The photographs were used in books etc., so I feel it is the best choice. We also had a crazy amount of lighting that we could change up. Three lights in the ceiling and at least one on each side of the item to keep the shadows away.

Finally, Harry Morgan’s Thoughts

I have always used thunder grey to white, but soft grey to white should work just as well. I think jet black to white would be too dramatic a difference between the light and dark area. Both are neutral colors and should not effect the color of the glass. The graduated works well for other things (wood, metal, porcelain) as well.