The nucleus of a human cell is not colored. It is a small, usually spherical organelle that is surrounded by a double membrane and contains genetic material in the form of DNA. While the nucleus itself is not colored, it can be stained with dyes such as hematoxylin and eosin to highlight its structure and location within a cell. The color of the stain can vary depending on the specific dye used and the staining protocol, but typically ranges from shades of purple to pink.