Defects in opal are, a colour inclining to that of the flower called heliotropium,[3057] or to that of crystal or of hailstones; salt-like grains intervening; roughness on the surface; or sharp points, presenting themselves to the eye. There is no stone that is imitated by fraudulent dealers with more exactness than this, in glass, the only mode of detecting the imposition being by the light of the sun. For when a false[3058] opal is held between the finger and thumb, and exposed to the rays of that luminary, it presents but one and the same transparent colour throughout, limited to the body of the stone: whereas the genuine opal offers various refulgent tints in succession, and reflects now one hue and now another, as it sheds its luminous brilliancy upon the fingers.
This stone, in consequence of its extraordinary beauty, has been called “pæderos”[3059] by many authors; and some who make a distinct species of it, say that it is the same as the stone that in India is called “sangenon.” These last-mentioned stones, it is said, are found in Egypt also, Arabia, and, of very inferior quality, in Pontus. Galatia, too, is said to produce them, as also Thasos and Cyprus. The finest in quality of them have all the beauty of opal, but they are of a softer brilliancy, and are mostly rough on the surface. Their colour is a mixture of sky-blue and purple, and the green hues of the smaragdus are wanting: those, too, are preferred, which have their brilliancy deepened by a vinous hue, rather than those which have their colours diluted, as it were, with water.
CHAP. 23.—SARDONYX; THE SEVERAL VARIETIES OF IT. DEFECTS IN THE SARDONYX.
Thus far we have spoken in reference to the stones, which, it is generally agreed, belong to the highest rank; in obedience, more particularly, to a decree[3060] that has been passed by the ladies to that effect. There is less certainty with respect to those upon which the men as well have been left to form a judgment; seeing that the value of each stone depends more particularly upon the caprice of the individual and the rivalry that exists in reference thereto; as, for example, when Claudius Cæsar was so much in the habit of wearing the smaragdus and the sardonyx.[3061] The first Roman who wore a sardonyx, according to Demostratus, was the elder Africanus, since whose time this stone has been held in very high esteem at Rome: for which reason, we shall give it the next place after the opal. By sardonyx, as the name[3062] itself indicates, was formerly understood a sarda with a white ground beneath it, like the flesh beneath the human finger-nail; both parts of the stone being equally transparent. Such, according to Ismenias, Demostratus, Zenothemis, and Sotacus, is the sardonyx of India; the last two giving the name of “blind” sardonyx to all the other stones of this class which are not transparent, and which have now entirely appropriated the name to themselves. For, at the present day, the Arabian sardonyx presents no traces whatever of the Indian sarda,[3063] it being a stone that has been found to be characterized by several different colours of late; black or azure for the base, and vermilion, surrounded with a line of rich white, for the upper part, not without a certain glimpse[3064] of purple as the white passes into the red.[3065]
We learn from Zenothemis that in his time these stones were not held by the people of India in any high esteem, although they are found there of so large a size as to admit of the hilts of swords being made of them. It is well known, too, that in that country they are exposed to view by the mountain-streams, and that in our part of the world they were formerly valued from the fact that they are nearly the only ones[3066] among the engraved precious stones that do not bring away the wax when an impression is made. The consequence is, that our example has at last taught the people of India to set a value upon them, and the lower classes there now pierce them even, to wear them as ornaments for the neck; the great proof, in fact, at the present day, of a sardonyx being of Indian origin. Those of Arabia are remarkable for their marginal line of brilliant white, of considerable breadth, and not glistening in hollow fissures in the stone or upon the sides, but shining upon the very surface, at the margin, and supported by a ground intensely black beneath. In the stones of India, this ground is like wax in colour,[3067] or else like cornel, with a circle also of white around it. In some of these stones, too, there is a play of colours like those of the rainbow, while the surface is redder even than the shell of the sea-locust.[3068]
Those stones which are like honey in appearance, or of a fæculent[3069] colour—such being the name given to one defect in them—are generally disapproved of. They are rejected also when the white zone blends itself with the other colours, and its limits are not definitely marked; or if, in like manner, it is irregularly intersected by any other colour; it being looked upon as an imperfection if the regularity of any one of the colours is interrupted by the interposition of another. The sardonyx of Armenia is held in some esteem, but the zone round it is of a pallid hue.
CHAP. 24.—ONYX: THE SEVERAL VARIETIES OF IT.
We must give some account also of onyx,[3070] because of the name which it partly shares in common with sardonyx. This name, though in some places[3071] given to a marble, is here used to signify a precious stone. Sudines says, that in this stone there is a white portion which resembles the white of the human-finger nail, in addition to the colours of chrysolithos, sarda, and iaspis. According to Zenothemis, there are numerous varieties of the Indian onyx, the fiery-coloured, the black, and the cornel, with white veins encircling them, like an eye as it were, and in some cases running across them obliquely.[3072] Sotacus mentions an Arabian onyx, which differs from the rest; that of India, according to him, presenting small flames,[3073] each surrounded by one or more white zones; in a manner altogether different from the Indian sardonyx, which presents a series of white specks, while in this case it is one continuous circle. The Arabian onyx, on the other hand, is black, he says, with a white zone encircling it.
Satyrus says, that there is an onyx in India of a flesh colour,[3074] partly resembling carbunculus, and partly chrysolithos and amethystos; a variety, however, which he altogether disapproves of. The real onyx, according to him, has numerous veins of variegated colours, interspersed with others of a milk-white hue; the shades of which, as they pass into one another, produce a tint which surpasses all description, and blends itself into one harmonious whole, of a most beautiful appearance.
Not unlike sardonyx, too, is sarda,[3075] a stone which also has, in part, a kindred name with it; but before passing on to it, we must first take some notice of all those precious stones which have a brilliancy like that of flame.