high-grade
[ hahy-greyd ]
/ ˈhaɪˈgreɪd /
adjective
of excellent or superior quality.
(of ore) yielding a relatively large amount of the metal for which it is mined.
verb (used with object), high-grad·ed, high-grad·ing.
to steal (rich ore) from a mine.
Origin of high-grade
First recorded in 1875–80