Final answer:
Subtractive color theory explains that the color seen is the light reflected by an object, not absorbed. Blue and yellow sections of the color wheel appear blue and yellow because they reflect blue light and red-green light respectively. Therefore, a substance absorbing blue light appears orange, and absorption of 420-430 nm light makes the gem appear yellow.
Step-by-step explanation:
Understanding Subtractive Color Theory
According to subtractive color theory, the color of an object is determined by the light it reflects. When white light—which is a combination of all visible wavelengths—shines on a surface, certain wavelengths are absorbed by the material while others are reflected. The color perceived by our eyes is the color that is reflected, not absorbed. For example, an object that absorbs all wavelengths except for blue will appear blue because blue is what is reflected and seen.
Color Absorption and Reflection on the Color Wheel
- The blue section of a color wheel will look blue because it will reflect blue light and absorb other colors (red and green).
- The yellow section of the color wheel will look yellow because it will reflect red and green light, which combine to form yellow, and it will absorb blue.
Following these principles, if a gem contains a substance that absorbs blue light, the gem would appear as its complementary color on the color wheel, which would be orange. If the substance absorbs 420-430 nm light (which corresponds to blue), the gem would appear yellow due to the reflection of the remaining red and green wavelengths that combine to create the perception of yellow.