1891, Colombo Apothecaries Company, “No”, in The Journal of the Ceylon Branch of the Royal Asiatic Society of Great Britain & Ireland[1], volume 10, Contains Society's Proceedings., page 36:
This is a good illustration to show what valuation by chevvu weight of perals means. The chevvu weight is simply three-fourths of the square of the weight (in mañchȧḍi) of the pearls.
1990, Anna M. Miller, “Appendix: Pearl Facts”, in Illustrated Guide to Jewelry Appraising: Antique, Period, and Modern, New York: Chapman & Hall, →ISBN, page 163:
Ceylonese A chevvu, chow, or tank is equal to 21.84 carats (24 ratis).
1992, Pierre Bariand, Jean-Paul Poirot, edited by Jean-Paul Poirot, The Larousse Encyclopedia of Precious Gems[2], Van Nostrand Reinhold, →ISBN, page 24:
[…] multiples such as the chevvu, chow or tank of 24 chevvu in Sri Lanka, the mesghal of 40 ratis in Persia, the tola in India, and the bali in Myanmar (Burma) (both worth 58.18 carats) of 64 ratis.
