The chocolate (coco) color in Frenchies has only recently been able to be identified in DNA testing, so in the past there was no way to test for this recessive gene. If two chocolates were bred, all offspring would be chocolates. If a chocolate was bred to a non-chocolate, all offspring would carry the chocolate gene. If chocolate carriers were bred, there was no way to know if the puppies carried the chocolate gene, unless a puppy was obviously a chocolate. Fortunately, it can be tested for now, which allows us to make more effective parings, depending on the colors we wish to produce. This litter from Ella (a lilac sable) and Heath (a chocolate brindle), produce three very handsome boys that are pure chocolate, chocolate brindle, and chocolate fawn. If Heath had carried the blue gene, some lilacs would have resulted. One of the chocolates are most renown for are their beautiful eyes, which are generally a golden yellow or hazel color.
Here is a litter with a beautiful chocolate brindle girl named Mugsy.