diamond color scale - SERP Analysis

https://www.gia.edu/gia-about/4cs-color

https://www.brilliantearth.com/diamond/buying-guide/color/

https://www.americangemsociety.org/understanding-diamond-color-the-4cs-of-diamonds/

https://4cs.gia.edu/en-us/diamond-color/

https://en.wikipedia.org/wiki/Diamond_color