I think the answer hinges on how your violet light will generated, ie what sort of bulbs you use.
In the continuous spectrum of light, visible violet merges next into "ultra-violet", in fact, they overlap a bit. If the violet light is monochromatic (a single wavelength), it will be in the 450nm to 380nm band. Ultra violet (A) is generally taken as 400nm to 315nm, Ultra-violet (B) as 315nm to 280nm, and UV(C) as 280nm - 200nm. All UV can be dangerous to human cells, and therefore humans, in one way or another.
I understand that most people see down to around 400nm, the beginning of UVA, although some people are known to be able to see down to to 315nm (UVB)
Safety legislation kicks in requiring eye protection from 400nm and on to shorter wavelengths. The most dangerous to human eyes is UVC, which is more the extreme non-visible end.
If you used violet light bulbs that were monochromatic (a single wavelength) of visible violet towards the shorter end of the spectrum, it could be harmful.
Now this is the bit I have less experience of. Apparently a violet colour can be made with a combination of red and blue light, which fools the human eye into seeing 'violet'. That would be much safer if it was generated that way.
So my question is - how would you propose making the violet light? Would you be able to guarantee it was being generated by a 'safe' combination of blue and red, and that it didn't contain potentially harmful wavelengths in the 400nm to 315nm range? I suppose if you use colour changing LED's it would be likely to be the red/blue combination, and maybe the manufacturer could confirm.
Another issue is that I believe eyes are not so sensitive at the violet end of the spectrum, so you would no doubt be having to turn up lights to a higher brightness than if they were white, though you wouldn't realise that!
I don't think it would be a safe thing to do unless you could be absolutely certain that whatever light sources you use did not emit wavelengths at the extreme violet end of the spectrum.
