Langgan 琅玕 is the ancient Chinese name of a gemstone which remains an enigma in the history of mineralogy; it has been identified, variously, as blue-green malachite, blue coral, white coral, whitish chalcedony, red spinel, and red jade
It is also the name of a mythological langgan tree of immortality found in the western paradise of Kunlun Mountain, and the name of the classic waidan 
Kaustubha, divine ruby or gem in Hindu mythology
Kaustubha (Sanskrit: कौस्तुभ, romanized: Kaustubha, lit. ‘crest jewel’) is a divine ruby or ratnam (gem) in Hindu mythology.[1] This gem is in