Note 2 — MINERALS.
Reading edition
A Carat is equal to four jeweller’s grains, seven grains of which are equal to six grains troy. To ascertain the value of wrought diamonds the weight must be doubled, about half being supposed to be lost in the working. This sum must be multiplied into itself, and the product by two. Thus to find the value of a diamond of twenty carats 20 × 2 = 40 × 40 = 1600 × 2 = 3,200l.