CONTORNIATE COINS.— Both for abundance and for superiority of curious interest, the NUMI CONTORNIATI, as they are termed in Latin works, hold the foremost place amongst the pseudo moneta of ancient times. It is probable that this word is derived from the Italian contorno, or from the French countour, signifying the outline of anything; since most of these coins actually exhibit, on the outer edge of both obverse and reverse, a circular line deeply engraved. The subject is treated of, with his usual mastery and with his accustomed justice to the labours of others, by Eckhel, who (in Doctrina, viii, 277) has divided it into six heads, viz. the characteristics, the types, the date, the use, and the merit, of Contorniates.
The following is a summary:—

I.—Peculiar Characteristics.— These are of a kind readily to strike the eye, and to distinguish this class of medals from the genuine coinage.
First.—The line on the edge of the coin, on both sides, marked circularly, and in the mode of a furrow; generally deep, in the place usually occupied, on the regular products of the Roman mint, by a ring of globules, which is rarely found on the coins now in the course of being described. This is the most certain token of a contorniate, and it is the circumstance , which, as already observed, probably gave rise to the term. There appears to be no doubt, that this line was made with a graving tool, after the coin was struck; for, on many specimens, the heads of the letters are divided by the instrument.

View whole page from the |Dictionary Of Roman Coins|