Two imperfections are less than 0,8 mm (0.031 in) in diameter may be as close as one diameter apart, provided that they are separated from any other imperfection by at least 13 mm (0.5 in).
两个直径小于0.8mm圆形欠缺,如果与其它欠缺的距离超过13mm,则它们之间的间距可小到1个直径。
另圆形欠缺按0.4, 0.8, 1.6, 3.2不同等级分别评定,主要决定于主欠缺和相邻欠缺的大小以及之间的距离关系。