The twelve images of FSAT trial color proofs above show six multicolor proofs and six monocolor proofs. You may notice how colorful many of them are. If you compare them to the actual stamps or a color picture of the stamps in a stamp catalog, you will also notice how different the colors are from the colors of the issued stamp. That, in a nutshell, is what trial color proofs are about - seeing a stamp in a diffent, and often much more colorful, version.
The FSAT trial color proof gallery has almost 1,000 high-resolution images. Each row on a gallery page represents the colors from a single sheet. The first three images, which are monocolor, show the three different color inks used in the sheet. The fourth image shows one of the five multicolor stamps in the sheet that combine these ink colors in a single stamp.