What defines the warmth or coolness of a color?

The warmth or coolness of a color is defined by hue. Hue refers to the pure color itself, which can be categorized on the color wheel as warm (like reds and oranges) or cool (like blues and greens). Understanding hue is essential for color theory in cosmetology, as it helps in selecting colors for hair, makeup, and skin tones that complement an individual's natural attributes.

While shade, tone, and value are important aspects of color, they do not specifically define warmth or coolness. Shade refers to a color mixed with black, making it darker; tone refers to a color mixed with gray, altering its intensity; and value refers to the lightness or darkness of a color. Therefore, while these elements are important in overall color perception, they are not responsible for the basic categorization of a color's temperature.