Board Thread:Questions/@comment-35990412-20180626014538/@comment-31048361-20180626020122

Because of the demand of each color. Black is typically the most favoured colour compared to pink, so it has a higher value than pink as it is in a larger demand.

Orange and green both aren't colors people love just as much. That's also why the more darker and "cooler" colors of rare spiked collars and wristbands are higher on the rarity scale.