Take a look at some of the many threads on this topic, they may help:
https://www.backyardchickens.com/t/679696/sexing-peachicks
https://www.backyardchickens.com/t/697670/sexing-peachicks-india-blues
https://www.backyardchickens.com/t/712423/can-i-get-some-help-with-color-and-sex...