Each of the 40 self-adhering metamerism stickers is finished with 2 different colors that integrate seamlessly with each other. For the correct D50 light source with CIE spectrum, both color fields appear identical (a minimal difference is apparent due to pigmentation).
If the light source substantially deviates from the standard D50 illuminant in spectrum or color temperature, both fields will reflect the incoming light differently and you will see 2 colors.
Adhering Lighting Indicator to press proofs allows everyone involved in the process to immediately determine which lighting is correct for making the color comparison.
Term definition:
Metamerism or metameric colors refer to color pairs that look identical when a defined illuminant is used and appear differently when another illuminant is used.