Sound and light are just two known manifestations of universal energy, and they could each be either harmful or helpful. I know practitioners that combine sound healing and color therapy. These healers are looking for the "color" bowls.
It's easy to convert the units of sound (Hertz - Hz) to units of specific diffraction of light (Nanometers Nm), but please don't forget that by simply converting units, you are not doing any alchemy, but only checking what equivalent of your tone will be manifested as a color.
If you are interested in discovering more about light therapy, I strongly recommend the "Spectro Chrome" encyclopedia by Dinshah Ghadiali.
I also would like to add, that during my research on color therapy and energy centers (aka chakras), I’ve found no evidence of the relationship between the seven colors of diffracted light and the seven main chakras.
Each chemical element has it's own spectrum of atomic emission. If you burn oxygen it will emit blue color, calcium - orange etc. Dinsha's theory describes the principle of color therapy as projection of desired color toward exposed part of the body that needs therapeutic attention. The color is being chosen based upon the lack of particular chemical elements.
Dinshah designed a special machine called Spectro Chrome projector, which was equipped with an incandescent bulb, optical condenser and most importantly five color filters covering a very precise spectral range of wavelengths. Twelve different combinations of colors are available by setting these filters separately or in band of two.