— borty , adj.
/bawrt/ , n.
low-quality diamond, in granular aggregate or small fragments, valuable only in crushed or powdered form, esp. for industrial use as an abrasive.
Also, boart, bortz /bawrts/ . Cf. ballas, carbonado 2 .
[ 1615-25; appar. metathetic var. of * brot (OE gebrot fragment); akin to ME brotel brittle, ON brot fragment ]