Fawn Cheeked is a combination of Fawn and (Grey) Cheeked. For beginners they can be difficult to distinguish from Chestnut Flanked White.
Fawn Cheeked females.
The Fawn mutation changes the black and grey pigments to fawn (brown) pigments.
The Cheeked mutation causes a loss in colour on the head, back and wings as well as a slight dilution of the black markings. But the most noticable effect is that the cheeks and flanks take the base colour. (i.e. Grey Cheeked have grey cheeks and flanks, and Fawn Cheeked have fawn cheeks and flanks.