Arthashastra
स्थूलं वृत्तं निस्तलं भ्राजिष्णु श्वेतं गुरु स्निग्धं देश विद्धं च प्रशस्तम् ॥
That which is big, circular, without bottom (nistalam), brilliant, white, heavy, soft to the touch, and properly perforated is the best.
english translation
sthUlaM vRttaM nistalaM bhrAjiSNu zvetaM guru snigdhaM deza viddhaM ca prazastam ॥
hk transliteration by Sanscript