There may be slight variations in glass color and the surface of your TheraBulb may show minor cosmetic blemishes. These may include small dimples, bubbles, areas of heavier or lighter coating, spots of darker or lighter color and minor marks on the bulb. Color variations and cosmetic blemishes may be more apparent when the bulb is on, but in no way negatively impact the performance or life of the bulb. All red light and infrared energy are produced by the filament inside the bulb.