XIII. INDIAN LAPIDARY 109 XIV. BLOWPIPE USED FOR THE MANUFACTURE OF RUBIES AND SAPPHIRES 118 XV. KIMBERLEY MINE, 1871 140 XVI. KIMBERLEY MINE, 1872 141 XVII. KIMBERLEY MINE, 1874 142 XVIII. KIMBERLEY MINE, 1881 143 XIX. KIMBERLEY MINE AT THE PRESENT DAY 144 XX. WESSELTON (open) MINE 145 XXI. LOADING THE BLUE GROUND ON THE FLOORS, AND PLOUGHING IT OVER 146 XXII. WASHING-MACHINES FOR CONCENTRATING THE BLUE GROUND 147 XXIII. DIAMOND-SORTING MACHINES 148 XXIV. KAFIRS PICKING OUT DIAMONDS 149 XXV. CULLINAN DIAMOND (natural size) 168 XXVI. LARGE AQUAMARINE CRYSTAL (one-sixth natural size), FOUND AT MARAMBAYA, MINAS GERAES, BRAZIL 196 XXVII. GEM-STONES (in colour) 226 XXVIII. OPAL MINES, WHITE CLIFFS, NEW SOUTH WALES 252 XXIX. GEM-STONES (in colour) 256 XXX. NATIVES DRILLING PEARLS 294 XXXI. METAL FIGURES OF BUDDHA INSERTED IN A PEARL-OYSTER 296 XXXII. SECTIONS OF CULTURE PEARL 297 GEM-STONES CHAPTER I INTRODUCTION Beauty, durability, and rarity: such are the three cardinal virtues of a perfect gem-stone. Stones lacking any of them cannot aspire to a high place in the ranks of precious stones, although it does not necessarily follow that they are of no use for ornamental purposes. The case of pearl, which, though not properly included among gem-stones, being directly produced by living agency, yet holds an honoured place in jewellery, constitutes to some extent an exception, since its incontestable beauty atones for its comparative want of durability.