People become aware of their core ray color by connecting with True Self.
When a person is not accepting of themselves, they allow their character to hide their core ray. Instead most portray a ray that they admire. This doesn’t tend to work out too well.
For example, Dean has a pink core ray. There’s a part of him that knows it but rather than face it and accept himself, he chooses to portray a knowledgeable purple. Dean’s father was a math professor and he always looked up to his dad while growing up. Instead of seeing Dean as highly intelligent, most of the people he runs into actually see him as being arrogant. The reason why Dean is seen as arrogant is because his core is insecure and he’s trying to portray knowledgeable. Someone who is insecure about their knowledge overcompensates by being arrogant.
When you truly know and accept yourself, you can examine your traits and match them to the core traits of an individual ray. Just be aware that most people have many rays that they’ve picked up from others. The core ray can be identified after the issues relating to other rays are worked through.