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Transactions of the Royal Society of South Africa. 
one given "rounded" octahedron belonged to Wesselton or Dutoitspan, 
albeit they would not differ about a number. 
2. Indesteuctibilitt of the Diamond (p. 21). 
Two cognate stories are given under this head, one from Pliny and the 
other from Ko Hung (fourth century a.d.) : 
" Pliny sets forth that the indomitable power which contemns the two 
most violent agents of nature, iron and fire, is Ijroken by the blood of a 
ram [? billy-goat, ' hircino which, however, must be fresh and warm. 
The stone must be well steeped in it, and receive repeated blows, and even 
then will break anvils and iron hammers unless they be of excellent temper."* 
According to the Chinese version, " The kingdom of Fu-nan (Cambodja) 
produces diamonds which are capable of cutting jade. In their appearance 
they resemble fluor spar. They grow on stones like stalactites, on the 
bottom of the sea to a dejDth of a thousand feet. Men dive in search for 
the stones and ascend at the close of the day. The diamond when struck 
by an iron hammer is not damaged ; the latter, on the contrary, will be 
spoiled. If, however, a blow is dealt at the diamond by a ram's horn 
[according to another reading, ' antelope or chamois horn,'] it will at once 
be dissolved and break like ice." 
Pliny may have read the property of toughness into what he had heard 
of the hardness of diamond. Diamond is anything but tough, and even 
carbonado, to say nothing of bort, is easily shattered by a blow. Careless 
handling in steel forceps will chip the edges of brilliants. The Chinese 
account is evidently a promiscuous mixing of the properties of calcite, 
quartz, pearl and diamond. But the great hardness of diamond has been 
exaggerated in modern times. Thus no less a philosopher than Sir John 
Herschel could describe diamond as " almost infinitely harder than any 
other substance in nature,"t a statement whose inaccuracy could have been 
rectified by a reference to Mawe's Treatise then in circulation. Mawe 
said, acutely enough, that "We know in general that, when two substances, 
greatly differing in hardness, come into collision, the effect produced by 
each upon the other is nearly in the ratio of their respective degrees 
of hardness ; the softer one will undoubtedly be the most affected, but the 
hardest will by no means escape unhurt. . . . With regard to the 
diamond we have the most authentic testimony that the Chinese and East 
Indian lapidaries are in the habit of polishing it upon a piece of corundum, 
the hardness of which is greatly inferior to that of the gem. "J Even Mawe's 
* A newly-rich visitor to the diamond fields knew better : " My 'usband says 
diamonds are not so 'ard as people say ; for 'e put some of mine on a lianvil and 'it 'em 
'ard with a 'ammer and smashed 'em hall to hatoms." 
f ' Preliminary Discourse on the Study of Natural Philosophy,' 1830, p. 237. 
X p. 20. Diamonds have been cut and polished in modern times with the powder 
of crystallised boron — " Avith entire success " according to Dieulafait. 
