Angela, I like that rainbow herringbone idea. . Thanks for posting your resulting pen !!!
What is the main wood in that pen, please ?
I think what you have done is more difficult to do that it would seem at first. . I can't really elaborate what I mean.
The lower barrel is perfect. . The cap (with the herringbone) seems discontinuous, in a way, but that seems to be an intrinsic aspect of the design unless you take specific measures to overcome it. . I think it can be overcome, but it might be a bit tricky.
At first I thought that Mark (above) had the solution, but he might have chosen the wrong set of photographs to illustrate his point (which is not altogether clear to me). . But I think he probably knows what he is talking about because he has achieved some stunning results with that kind of very fine segmenting work. . I think we should press him to have another go at explaining ....

!!!
I think things would look better if there was continuity to the same color veneer on both sides of "the meeting point" if you know what I mean.
But exactly how you achieve that, I do not presently know.
One other thing relates to the grain structure of the main wood ... and that's why I asked you about what would you used.
I have the feeling that with a finer grained main wood the result would look better. . As it is, I think that the coarse grain detracts from the herringbone effect.
Overall, I think you have done an excellent job of cutting and gluing to achieve the herringbone effect, and I hope you will attempt and show some further refinements of this idea.
Thanks for showing, and I really would like to know what wood you used, please.