I think this thread had some good examples of each of the colors taken in the same location with the same camera, so it should minimize the number of variables at play:
https://saberforgeforum.com/forum/saber-forge-saber-gallery/1148-color-index
The difference between the mint green and the cyan is probably one die. If you're looking for a green-blue blade I would go mint green, but if you want a blue-green I would go cyan.