In the english language there are a plethora (Crap Load) of different words to describe colors that all basically mean the same thing.
But yes violet would be a lighter purple - somewhere between lilac and purple lol
You're right - there's a gazillion colour nuances to pick from.
But the key thing in this context is that Purple has a lot more intensive glare in interaction with light than Violet. This is what we are seing in our crystals - interaction with light.
And because Violet is more 'flat' or 'dead' than Purple, this is probably the main reason why we see a much more subtle/less pronounced AR-glare in this sapphire: Not because of the shift from red to blue hue, but because of the (lesser) intensity of the colour Violet.
Hope that makes sense as to why I felt it had some value when assessing AR-coatings..
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)