Yuki

Yuki (雪, snow) is the Japanese go term for the grade of shell stones that many consider the perfect White stones. Shell stones as a class are preferred to glass or plastic.

Yuki will have the grain run straight across the stones without a bend. Lower grades of stones include tsuki (curved grain on stones) and jitsuyo (which have an indistinct grain).

Important in the aesthetics of Go. -- Tim Brent

Yuki grade size 30 stones

Single yuki stone