Lamp shades are created in batches and individually hand blue into molds. Each glass, silk or replacement lampshade will be unique to its own batch. Even though each batch will look similar to another giving items a similar look. There will be subtle differences. When fabric or silk shades or chandelier shades are manufactured each batch or run will be unique. The color of the fabric will be different, the width of the binding or finishing will be slightly different. Even the color of the metal will be slightly different.
Metal molds are used for the manufacturing glass shades. Glass can be machine blown or hand blown. Even machine blown glass will differ from run to run. While the molds are manufactured to an exact specifications they will still have a slightly different shape or depth to the piece. We always ship all items ordered at one time. we do not break batches because there is a chance the items will not be an exact match. With hand blown items each piece is blown at the same time by the same person for maximum uniformity. The items will all be manufactured from the same mold, and ground to the same depth.
Reverse painted lamp shades must also be purchased at the same time. The paints for hand painted shades are hand mixed, so each mixing will also be slightly different. Differences in firing time and depth of color will also vary from item to item.