Imagine 12 total colors, lined up in a row.
6 are pure colors: yellow, red, magenta, blue, cyan, and green.
6 are connector colors: orange, red magenta, violet, blue cyan, green cyan, and yellow green.
Each of those 12 colors has 9 values that form a column:
the pure color in the middle, 4 lighter tints below, and 4 darker shades above.
Value 1 is the lightest, value 5 is the pure color, and value 9 is the darkest.
Like a rainbow, the 12 color columns transition to each other. Add:
2 transition colors between each column at level 5,
1 transition color between each column at levels 4 and 6, and
1 transition color between every other column at levels 3 and 7.
A chart of 168 colors is the result. These colors represent the chart populated with Kona Cotton by Robert Kaufman Fabrics. With Kona's palette of 340 colors, the chart is missing only 11 - not bad. The color representation is not perfect, but it's dang close.