B. I like this discourse very well but have no occasion for so deep an inspection into the matter. I have but 2 or 300l., to lay out and I heare that the market at this time is at a midling pitch & therfore I had rather heare from you upon the intrinsec causes & such as lye within the stone it self.
A. I am content. You must therfore know that these intrinseck causes are principaly foure, vizt. weight, extent, colour or water, cleaness from faults, & to theise you may adde the mode and workmanship of the cutting.
B. When I bought my ring I did not divide my consideration into so many branches: methought it made a fine shew in general & I bid 85, 86 & 87l., for it, & the merchant swore he could not afford it so & seemed to goe away once or twice and thereupon I gave him 90l., & he told me that he would give me 85l., for it at any time within a twelvemoneth & defys me to match it anywhere for the money I gave him. Besides I had shewed it to 2 or 3 friends, who all, to shew their skill, made some special animadversions upon the business & told me I could not be much out if I gave between 80 & 90l., for it; and this is all the art I had. I expect now to be wiser from you.
A. I told you there must be four intrinsick causes of dearnesse & cheapness, vizt. Weight, Extent, Colour & Clearness. As for the weight you must get you a pair of Scales that will weigh with certainty to less then a quarter of a grain. As for extent you must get a piece of Muscovia glasse or very fine horne, wherein must be a square drawn of an inch in the side & the said Square divided into 400 Squares, dividing each side into 20 parts by the finest lines that can be drawn, making every fourth division in a line somthing bigger then the rest for distinction sake. Thirdly you must have 5 or 6 diamonds to lye constantly by you, each of a several water, & you must have in the opinion of the best jewellers the proportion of value which the said waters do beare one to another, as for Ex.: Suppose a stone weigh a graine & being of the best water is worth 25s, of the black water 20s, of the red 16s, of the yellow 14s, of the blewish 13s, of the brownish 12s &c. Fourthly you must have