The Skull Ring
Origin, history, and properties
According to Lee Falk
As narrated in The Phantom's Ring, it is made of gold, it is ancient and it was given to the 1st Phantom by the the jungle kings. The appearance of the ring has varied through the publication of "The Phantom", but it has always been giving a Skull Mark when the Phantom hits a criminal with it. In the Moore/McCoy/Lignante stories, the ring was worn at the right ring finger, but with the start of the Barry era, the ring is worn at the middle finger.
According to Team Fantomen
The ring is a lot older than the Phantom. There are several conflicting theories about the origins of the ring, but as much is certain that it once belonged to emperor Nero and was used as a key to a special vault in the catacombs under Rome which contained a jewel.It came into the possession of the first Phantom through the Swiss scholar Paracelsus, who handed it over to him shortly before he died.
Even though it is not clear how come, it is known that the ring cannot be melted down, several fruitless attempts has been done during the centuries. The ring could also be used as a kind of catalyst; if put in a fire, the flames increases, yet it is not warm when picked out.
According to Phantom 2040
In Phantom 2040, the ring has a somewhat different appearance compared to the comics appearance and it could be used to open the entrance to the Phantom's secret base in the city.
According to The Phantom (1996 film)
The ring is the control device for three skulls of immense power, given to the first Phantom by the Touganda shortly after their first meeting.
According to The Phantom (2010 TV pilot)
Nothing about its origin is explained in the pilot, but the Phantom-under-training has to pick it out of a fire without burning his hand to prove that he is the Phantom. He also wears the ring at the ring finger instead of (as in the comics since the early 1960s) the middle finger.