And other factors, like lighting at the time the photo was taken, and then when the object is in your hand, what kind of lighting are you using when examining it. I've seen wild differences in color from inside a house, to lighting in a workshop that are a surprise, but they exist.
I think it's called metamersim?
Also, your own eyes' perception, I have this color blindness that when a color is in isolation on a white background, I can tell what it is, but put it with other colors, especially those that have red and green, and it gets real confusing. Comet cleanser looks like blood, purple flowers look brown, but change the light and it looks "normal".
My wife is always correcting my color coordination, but whatever ... I know I was real sad when I was told I couldn't be a fighter pilot.
They have these formulas as to light saturation etc that assign a number to a spectrum of light ...
But ... I think the best you can do is get an approximation, and then see it in person under your own light conditions.
As you can imagine, I don't worry about it too much, if I can get in the ball park I'm happy.