If this is your first Tiffany lamp purchase, please read the following: The issue of whether the material in the shade is plastic or glass. Please rest assured, this item, and any other you may choose to obtain from us, will be stained glass, and only stained glass. If a manufacturer chooses to unite the pieces of stained glass using a combination of copper foil and molten solder alloy — as we do — there is simply no plastic that will properly withstand the heat. Unequivocally, we use stained glass, employing the copper foil manufacturing technique which is essentially unchanged from the Tiffany Studios at the turn of the 20th Century. We occasionally field “it feels like plastic” complaints, and in every instance, we must explain that small pieces of glass, ‘floating’ in a cushion of solder and copper do not have the sensory experience of window panes or wine glasses, as an example. Regarding your collection of stained glass, I’ll mention this…. If you are referring to lamp shades, I doubt you will find any discernible difference in weight. Regarding window frames, there may be a difference. You may own some products produced by what is called the ‘came’ method, in which a much larger ‘H’ shaped channel of metal alloy is used to produce the item. Came technique is normally associated with larger flat panels, and the density of came certainly exceeds the density of a comparable amount of molten solder. Please google “why stained glass feels like plastic”. You will find thousands of listings on that issue. Attached is the hyper link to the Google search: https://www.google.com/?gws_rd=ssl#q=why+stained+glass+feels+like+plastic