Let’s return to golden blood. In truth, the eight common blood types are an oversimplification of how blood types actually work. As Smithsonian points out, “[e]ach of these eight types can be subdivided into many distinct varieties,” resulting in millions of different blood types, each classified on a multitude of antigens combinations.

Here is where things get tricky. The RhD protein previously mentioned only refers to one of 61 potential proteins in the Rh system. Blood is considered Rh-null if it lacks all of the 61 possible antigens in the Rh system. This not only makes it rare, but this also means it can be accepted by anyone with a rare blood type within the Rh system.

This is why it is considered “golden blood.” It is worth its weight in gold.

As Mosaic reported, golden blood is incredibly important to medicine, but also very dangerous to live with. If a Rh-null carrier needs a blood transfusion, they can find it difficult to locate a donor, and blood is notoriously difficult to transport internationally.