I've invented a Celtic pattern for this board. I took a thin border pattern from a book on Celtic design, doubled it and added a connecting center link. It reminds me of a shield pattern or armour decor. The alternating black and dark blue within a green border are a subtle gradation.

In CB1018 the interior element of this pattern is reversed, with the colors taking the place of the white areas,
and vica versa. The outline is grey
instead of green.