They were white and grayish, but not solid. I had to give them away, so cannot observe the colors change... I called them splash, and the first one, a penguin color.
"Splash" is the name for a specific color of chicken caused by having two copies of the blue gene. In future I suggest not calling a chicken splash unless you know they have that particular set of genes. (A chicken with a black parent cannot be splash.)
The come from a white and a black rooster, and a gray, white and a buff hen.
What is the science of mixing colors?
With that set of chicken colors, you pretty much need an entire course in chicken genetics to understand all the options
There is some information on chicken genetics here:
http://sellers.kippenjungle.nl/page0.html
And a chicken genetics calculator here:
https://kippenjungle.nl/kruising.html
What I like to do with the calculator is just change one gene (one of the dropdown boxes), and look at how the picture of the chicken changes. And then change another one...
Some of the genes make changes that are easy to understand, like B (barring) that makes white bars across the feathers of the chicken, or S (silver) that changes all gold color on the chicken to white. Some others are more complicated, because they interact with other genes to change how the colors are distributed on the chicken. The first half-dozen or so are the most complicated ones, with the ones further down the list being less confusing (at least to me).
In the calculator, the genes marked with + are called "wild type," meaning the ones that the wild Red Junglefowl ancestors of chickens have. They are also the default settings.
The calculator can be used to put in the genes of two chickens and see what offspring they might produce, but I usually have more fun just changing genes and watching the pictures change
How do I get a buff? Do I need a buff rooster and a buff hen? I did not get a buff chick, but I got 2 blacks, although I had a black rooster and no black hen.
Breeding two buffs should give you buff chicks most of the time. Buff is genetically complicated, so crossing a buff with another chicken will often give not-buff chicks.
When you cross a black chicken to any other chicken, it is very common to get black chicks. It doesn't always happen, but it is quite common.