Pugs come in 2 colours, black and fawn (which can be silver fawn or apricot fawn as well). The chart below shows how it works. It's quite easy once you get the hang of it. Basically, fawn and fawn together will always have fawn puppies. The differences in the shades of fawn are simply that -  just differences. Apricot is deep red/fawn, and silver is usually fawn with no black mask, trace or guard hairs.

Black comes in 2 types, pure black, or hybrid black. You can't tell just by looking. Mating a PURE black (quite rare these days) to ANY colour Pug will result in all black pups, as black is dominant (shown by the capital Bs and small fs in the picture). A hybrid black (carrying both black and fawn genes), when mated to a fawn, will have a mixture of fawns and blacks, as will two hybrid blacks, but some of the black puppies will be pure black, and some hybrid black. A pure black and a hybrid black will have all black puppies, but some will carry the fawn gene, so if mated with a fawn or another hybrid black, would be capable of producing both fawn and hybrid black pups. This means that a black to black mating will not always produce all black puppies.

One of our black bitches, Betty, is definitely hybrid, as she has had fawn puppies, even when mated with a black dog. One of our other black girls, Molly, has all black pups, even when mated to a fawn dog, so we can be pretty sure she's a pure black