I live in New Engand where bluestone is common. When I order, I specify the color mix that I want...either "bluestone" or "full color bluestone."
"Buestone" is all biue. Fairly monochromatic. Nice color, actually a beautiful color, but, well...monochroomatic.
"Full Color" offers a mix. It's still bluestone, but the colors range from the standard blue to subtle greens and even magenta. The magenta, while pretty, tends to be sightly flakier, or softer. Still, it's nice in the color mix.
Look at "Pennsylvania" and "New York" bluestone. Slightly different colors variations in each, at least in my stone yard.