The Referral system started with Google a while back. And then Google Introduced Firefox Referrals which didnt allow the feature to be used by internation users. But they finally allowed the system internationally. But the referral images were all in white color. A few days back some colour image options were introduced. Not so impressive but yes they might help some colorful blogs and sites.

But ultimately they have to make the referrals colour-free and the colour options to the users.

These are the added ones: