Here's why we don't have a definitive answer:
* Ancient descriptions are limited: Ancient texts don't provide detailed physical descriptions of the gods, focusing more on their powers and roles.
* Artistic interpretation varied: Different artists portrayed Demeter in different ways, with varying hair colors. Some depicted her with dark hair, while others used blonde or auburn.
* Hair color wasn't a major focus: Ancient Greeks weren't as obsessed with physical appearance as modern cultures. Hair color wasn't a defining characteristic for the gods.
So, while Demeter might have been imagined with different hair colors, we can't say for sure what it actually was.