Coffee Roast Color Wheel Chart compatible with original Agtron SCA Color Tiles, a set of 2

I got this in the process of learning to roast, prior to picking up a colorimeter device. I found it to only be accurate in terms of getting a very general idea of whether your coffee is light or dark. Which one could discern anyway by looking at the grounds without this sheet.It doesn't allow nuance to be detected, and the colors change in different lighting conditions (just like paint swatches will do, which is why you bring them to your room that you're wanting to paint and look on a few different days, rather than only trusting the color while viewing the swatch in the store).With respect to the seller, who I'm sure is trying to help others with this product, I would personally advise people to judge their desired roast level based on flavor of bitterness or not, at least 4-5 days after roasting. That will give a better idea of what you're aiming for.

I sometimes roast coffee beans at home, so this is useful for me. I like medium dark the best, so I can check this color wheel while I’m roasting beans.

While it might be useful for the novice roaster, it has limited utility and is extremely expensive. Websites that sell green coffee beans have better pictures on their websites.