#metric_grain__grain  used for pearls or diamonds: 50 mg or 1/4 carat
  supertype:  metric_weight_unit__weight_unit  a decimal unit of weight based on the gram
  part of:  decigram
  part:  milligram__mg  1/1000 gram
     part:  microgram__mcg  one millionth of a gram

No statement uses or specializes metric_grain; click here to add one.