CHAP. 37.—IASPIS; FOURTEEN VARIETIES OF IT. DEFECTS FOUND IN IASPIS.
Iaspis,1 too, is green, and often transparent; a stone which, if surpassed by many others, still retains the renown which it acquired in former times. Many countries produce this stone: that of India is like smaragdus in colour; that of Cyprus is hard, and of a full sea-green; and that of Persia is sky-blue, whence its name, "aërizusa."2 Similar to this last is the Caspian iaspis. On the banks of the river Thermodon the iaspis is of an azure colour; in Phrygia, it is purple; and in Cappadocia of an azure purple, sombre, and not refulgent. Amisos3 sends us an iaspis like that of India in colour, and Chalcedon,4 a stone of a turbid hue.But it is of less consequence to distinguish the several localities that furnish it, than it is to remark upon the degrees of excellence which they present. The best kind is that which has a shade of purple, the next best being the rose-coloured, and the next the stone with the green colour of the smaragdus; to each of which the Greeks have given names5 according to their respective tints. A fourth kind, which is called by them "boria,"6 resembles in colour the sky of a morning in autumn; this, too, will be the same that is known as "aërizusa."7 There is an iaspis also which resembles sarda8 in appearance, and another with a violet tint. Not less numerous, too, are the other kinds that are left undescribed; but they are all blue to a fault,9 or else resemble crystal in appearance, or the tints of the myxa10 plum. There is the terebenthine11-coloured iaspis also; improperly so called, in my opinion, as it has all the appearance of being a composition of numerous gems of this description.
The best of these stones are set in an open bezel, the gold of which only embraces the margins of the stone, leaving the upper and lower surfaces uncovered. One great defect in them is a subdued lustre, and a want of refulgence when viewed from a distance. Grains also like salt appear within the stone, and all the other defects which are common12 to precious stones in general. Sometimes they are imitated in glass; a fraud, however, which may be easily detected, from the material throwing out its refulgence, instead of concentrating it within itself. To this class also belongs the stone called "sphragis,"13 which is only reckoned as belonging to the domain of precious stones, from the circumstance that it is the best of all for making signets.14
(9.) Throughout all the East, it is the custom, it is said, to wear iaspis by way of amulet. The variety of this stone which resembles smaragdus in colour is often found with a white line running transversely through the middle; in which case it is known as "monogrammos:"15 when it is streaked with several lines, it is called "polygrammos."16 Here, too, I may take the opportunity of exposing the falsehoods17 of the magicians, who pretend that this stone is beneficial for persons when speaking in public. There is a stone also that is formed of iaspis and onyx combined, and is known as "iasponyx."18 Sometimes this stone has a clouded appearance; sometimes it has spots upon the surface like snow;19 and sometimes it is stellated with red spots.20 One kind resembles salt of Megara21 in appearance, and another is known as capnias,22 and looks as if it had been smoked. We have seen in our day an iaspis23 fifteen inches in length, of which a figure of Nero was made, armed with a cuirass.
