Is the refractive index of red or violet greater?

You can trust me on light, more than anyone else. The refractive index of a color of light, depends on its wavelengths. as. E = hf, where E is the energy of the photon and f is the wavelength. read more

The refractive index of red is smaller than the RI of violet (in air--->glass). The refractive index of light in transition between two materials depends on the speed of light in them and is calculated by the ratio n = V1/V2, where V1 is the light speed in the first material and V2 in the second material. read more

Violet light slows down even more than red light, so it is refracted at a slightly greater angle. The refractive index of red light in glass is 1.513. The refractive index of violet light is 1.532. read more

The index of refraction is always greater than or equal to 1, because $c$, the speed of light in vacuum, is always greater than the speed in a material. So, as you have stated, red light has a lower index of refraction than blue light since it also has a shorter wavelength, so lower index of refraction corresponds to higher speed in a material. read more