In addition to grading crystals based on size, condition and clarity, there are characteristics in Quartz that make them highly collectible. One characteristic is a Japan law twin formation.
Japan Law Twin, also known as Weiss Law Twin and Twinning Crystal Quartz, is an extremely rare quartz variety. It is defined as having two crystals that meet at an angle of 84°33'; as well as having parallel prismatic faces (resulting in a “V” formation)
