#opaque_gem  a gemstone that is opaque
  supertype:  gemstone__gem__stone  a crystalline rock that can be cut and polished for jewelry
  subtype:  chrysoberyl  a rare hard yellow green mineral consisting of beryllium aluminate in crystal form; used as a gemstone
     subtype:  alexandrite  a green variety of chrysoberyl used as a gemstone
  subtype:  opal  a translucent mineral consisting of hydrated silica of variable color; some varieties are used as gemstones
     subtype:  black_opal__blackopal  a dark colored opal with internal reflections of green or red
     subtype:  fire_opal__girasol  an opal with flaming orange and yellow and red colors
     subtype:  harlequin_opal__harlequinopal  a reddish opal with small patches of brilliant color
  subtype:  cat's_eye__cat'seye  any of various gems (as chrysoberyl or chalcedony) that reflect light when cut in a rounded shape
  subtype:  precious_coral__coral__red_coral__redcoral  the hard stony skeleton of a Mediterranean coral that has a delicate red or pink color and is used for jewelry
  subtype:  jadestone__jade  a semiprecious gemstone that takes a high polish; is usually green but sometimes whitish; consists of jadeite or nephrite
     subtype:  jadite
  subtype:  jasper  an opaque form of quartz; red or yellow or brown or dark green in color; used for ornamentation or as a gemstone
  subtype:  lapis_lazuli__lapislazuli__lazuli  an azure blue semiprecious stone
  subtype:  turquoise  a blue to gray green mineral consisting of copper aluminum phosphate; blue turquoise is valued as a gemstone

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