I assume you mean Easter Eggers, not True Ameraucanas? If you aren't sure what the difference is, they're Easter Eggers. Easter Eggers are multigenerational hybrids of Ameraucanas and are very frequently mislabeled as the real deal. True Ameraucanas are rare, expensive, and when sold will be prefixed with a color variety, e.g. a "Blue Ameraucana" or a "Wheaten Ameraucana".
About 80% of them can be expected to lay a blue or green egg (the other 20% will produce tan/pink/tinted). The blue egg gene is dominant, so those who lay a colored egg have at least one copy of the gene, but whether they have one or two will be impossible to tell until they are test bred. Those with two copies will produce 100% green egg laying offspring, those with one copy will produce 50% green and 50% brown egg layers. The 20% of Easter Eggers who produce pink/tan/tinted eggs will produce 100% brown/tinted/pink/whatever shade laying offspring when breed with another brown egg layer.