Diameter of the free form button about 10mm.
Communication, listening and understanding are the topics for which the blue chalcedony is used in modern stone healing. Blue Chalcedony is therefore also called "speaker stone".
The terms "Calchedon" and "Carchedon" are first used by Pliny the Elder in his Latin Naturalis Historia in the 1st century AD. Which stones have been described here, however, cannot be clearly identified on the basis of the descriptions. Over "intermediate stages" like Calcedon, Calzedon, Chalzedon or Kalcedon the name changed to the today common Chalcedon.