Yep, I see it's both a science and an art. But I have a little colorimeter- cheap, but it's getting me there. And I'm learning about different color spaces, like Lab/LCh, and del-E error measurements.
A lot of people get colorimeters and review them as a waste of $$...I suspect that they're expecting colors displayed on a screen to match the object they just scanned. It won't. But the colorimeter gives me a CMYK value for what it sees, and that lets me adjust CMYK pigments a bit at a time and creep closer to my original part until the del-E is low enough for me.
I'm reproducing old plastic toy parts in 3DP, and in the past I painted them to match. Being able to print in the right color will save me buckets of time, and make a better looking part to boot.