I have to admit to already having a nearly perfect one for my taste, even if not particularly exotic-

A Cedar Blue Vac with a very nice chevron band sterling cap.

The only thing I dislike about this particular pen is its sort of scratchy XF nib. I'm tempted to switch it out with a stub I just bought, but am not sure how correct it is on that pen and wonder if I should maybe just drop an ordinary F or MAYBE M on it.

Although I've not had any super exotic 51 colors other than a demi coco, I think Cedar Blue may just be my favorite of the ones I have owned. Between the Lustaloy, Gold Filled, and Sterling caps I like the latter best as they are a nice dress-up from Lustaloy but at least I think on the Cedar Blue complements the pen very well. I do have a liking for the wartime gold filled silver caps, and they get bonus point because they're often so ugly "in the wild" that someone who doesn't know what they are often knocks down the price on them...