In the Cut Collection of paper piecing patterns, I include four colourways in Kona Cottons: green, purple, red, and yellow. They work best on a white, off-white, black, or near-black backgrounds. Except for the yellow, which works best on black or almost black. The rationale for all the colourways is this: Because the gemstones are transparent, they reflect the background colour.
To help with the fabric selection, I used the Play Craft Palette Builder, which allows you to upload an image and it spits out Kona colours that come from pixels in that image. What a fabulous tool; I wish I knew about it when I was designing Crow Quills Analog four years ago! I cross-referenced it with my Kona Colour card to be sure that what I was seeing on screen was accurately represented in the fabric selection.
Below is a chart of five additional colourways for The Cut Collection of paper-pieced gemstones. The white is the exception in this set. Kona Snow is not recommended as a background, lest lightest shade of the colourway disappear into it.
With the yellow colourway, you may notice the darkest shade is not even yellow; it’s green. That is the result of the black background being reflected into the stone, and then perceived by your eye to be green. When you “add” black to yellow, you will start to get a green shade.
Likewise, if I put a clear colourless stone, like a diamond, onto a coloured background, it will change the colours in the stone. The middle row of gems in the image below are all clear, colourless stones, but reflect their coloured backgrounds. Various tints emerge in the colour scheme. The bottom row of gems do not reflect any of their background colour; the result is a gemstone disassociated from its surroundings.
If you would like to learn more about “adding” and “subtracting” colour, I highly recommend Josef Albers’ Interaction of Color. It brings one’s perspective on colour to a whole new level. Albers presents qualitative equations and proofs about colour to show you how you perceive; it will blow your mind. Or find some transparency inspiration on Pinterest.