316	SMARAGDUS.
	the Emerald itself to other gems." Their extreme hardness pre­vented their being engraved. All these characters, but especially the last, indicate this gem as the Green Buby, a very rare variety of the Precious Corundum, which indeed ought rather to be called a Green Sapphire. One of large size, belonging to the Hope Collection, exactly coincided with Pliny's description, its colour being the darkest green, aptly designated by the term " austeritas," but far from pleasing ; and its freedom from flaws, as contrasted with a true Emerald of the same magnitude, was particularly striking. For no precious stone is more liable to defects than the latter ; even the smallest Peruvian Emerald when cut will show one or more flaws within its substance : indeed their total absence is in itself enough to excite suspicion that the gem is merely a glass imitation ; for no other precious stone can be more exactly counterfeited by a paste. It must not, however, be forgotten that the old jewellers, like De Boot (ii. 52), describe their " Oriental " Emerald (" brought from the East Indies, but where found, not known ")9 as both far harder and far deeper in colour, and of a clearer substance than the Peruvian ; moreover, always small in size, rarely equalling a hazel-nut. The Ural and Altai mountains have of late years furnished true Emeralds of the finest quality ; the Scythian of Pliny may perhaps have been derived from that very source, brought down by the barbarian goldseekers in those regions (the Arimaspi) to the Greek colonies around the Black Sea, or to the Persians on the Caspian. Next in value, as well as in the locality of their origin, were the Bactrian, found, it was said, in the crevices of the rocks during the prevalence of the Etesian winds : " for then especially did they sparkle in the ground when those winds swept away the sands." These, however, were much smaller than the Scythian sort. Dionysius Periegetes de­scribes the Indians as gathering both '"verdant Beryls" and grass-green Jaspers out of the gravel of their torrents ; appa­rently including Emeralds under the former designation.