Lightstreams Glass Tiles are hand-crafted, art quality glass. All stated sizes are nominal. It is inherent that there will be differences in color, shape, and texture from tile to tile, from manufacturing run to manufacturing run. Samples are intended to give you an idea of the general look, feel, and quality of the glass, but, especially for the Jewels tiles, color and internal texturing may be very different from piece to piece and manufacturing run to manufacturing run of the same part number (like dye lots in fabric). Therefore, please order enough tile with your initial order so that you don't run short and have to order additional tile which may come from a different manufacturing run. We suggest ordering 10% more than the exact amount of tile you require.