The outer knobs on my pristine set are (I believe) what you are calling "almost purple". The inner knobs are Hershey's-milk-chocolate brown. The left two have recessed white indicator lines, the others do not.
The pictured-above spare knobs are all brown. Two distinct shades, Hershey's milk and Herhey's Extra Dark. The two outers in the middle are "milk", the remainders "dark". The middle inner knob is milk, the two others are dark. No "almost purples".
I think the "almost purple" is an aged Extra Dark. It looks like it would polish off. I won't try it on my good set, you might see if it polishes off of one of yours. Maguire's Cleaner Wax works best.
All the pictured knobs above came off GE 810's. My 2nd set and a couple of junkers. I doubt one color is more correct than another. If your concern is that your knobs came off of some other GE product, I would guess not. More likely various production runs, like your oval vent holes. Probably it really matters that they all match each other, else the TV will look kluged together. If I can help you attain a matched set with any of the above knobs, let me know. As you know, some of them have different inner diameters than others. I have most of a set for my 2nd set, but not quite.
I'm almost positive Steve McVoy has an 810 in the museum, as nice or nicer than mine, but I don't see it on his website. I pretty clearly remember it in person. An oversight perhaps. If you're out there Steve, perhaps you can check yours for the white indicator lines and what colors you have.