The precise range of wavelengths for the color indigo can vary depending on the context, as there is some variation in how indigo is defined and perceived. However, in the context of the visible light spectrum and the standard color wheel, indigo is commonly described as having a wavelength between approximately 450 nanometers (nm) and 420 nm.
It's worth noting that there is some overlap and subjective interpretation when it comes to the boundaries between colors in the visible spectrum. Different color systems and interpretations may vary slightly in their categorization and naming of colors.