"Create a high-resolution image featuring a vertical rectangular gradient inspired by the reflective or data layer on the underside of a CD. The gradient should capture the iridescent, shimmering effect typically seen on CDs, showcasing a spectrum of colors that blend smoothly from one to another. The colors should include, but not be limited to, vibrant hues of blue, green, purple, pink, and yellow. The overall effect should be visually striking and dynamic, resembling the way light reflects off a CD's surface. The gradient should fill the entire rectangle."