Slate. They start out a cute little brown and then grow slate colored feathers but they aren't just a solid slate blue. They have subtle other colors and differences between them. It's an interesting color from keet to adult. Violet is somewhat similar and also starts out as tan keets and then grow to their interesting mix of shades.
Of course everything is better with the pied gene on it but I'd take a pied slate, violet, or coral blue over pied pearl any day.
Where are you getting keets? It's getting kind of late in the year. I know guinea farm has a good portion of theirs not laying. You can get eggs shipped to you but you won't get much choice in color. Most just offer a certain mix of colors depending what they run together. Odds are if you really want certain colors you'll have to wait until spring unless you want common colors.
The lady who gave me a pair had ALL colors of guineas on her property. Pied Slates were the ones that caught my eye.. fortunately she managed to catch a pied Slate and gave him to me with a pied Pearl hen.
I have to say.. they had babies now nearly full grown and one of them is a regular Pearl.. she does seem very pretty with the complex dotting all over. Unfortunately all of the other guineas are really mean to her, including her parents.