Guinea eggs are very hard, I have seen dogs try to eat them, but were unsuccessful. When using them for cooking, it is really hard to get them cracked.
Guineas lay a variety of colors. Their eggs can be white (Not fully white like chickens), brown, or tan. They might have spots or speckles. There may be a ring of speckles then a plain tan ring and then another ring of speckles. (I have a hen which lays eggs like this) The end of the guinea's egg is pointed. A guinea egg should be a little smaller than a medium chicken egg I'd say.
I assume guinea's are just like chickens to where each hen can lay a variety of each color. Either white, brown, or tan eggs. With spots or speckles or none.
I get mainly tan eggs with speckles. If you want I could post some pictures.
View attachment 1741939 Most of my royal purples are laying various shades of light tan some with speckes - but today got this - green on one side shading to tan.