Mindblown: a blog about philosophy.

SPINEL labours under the serious disadvantage of being overshadowed at almost all points by its opulent and more famous cousins, sapphire and ruby, and is not so well known as it deserves to be. The only variety which is valued as a gem is the rose-tinted stone called balas-ruby (Plate XXVII, Fig. 3), which is […]

TOPAZ is the most popular yellow stone in jewellery, and often forms the principal stone in brooches or pendants, especially in old-fashioned articles. It is a general idea that all yellow stones are topazes, and all topazes are yellow ; but neither statement is correct. A very large number of yellow stones that masquerade as […]

THE species to be considered in this chapter includes the varieties emerald and aquamarine, as well as what jewellers understand by beryl. It has many incontestable claims on the attention of all lovers of the beautiful in precious stones. The peerless emerald (Plate I, Fig. 5), which in its verdant beauty recalls the exquisite lawns […]

RANKING in hardness second to diamond alone, the species known to science as corundum and widely familiar by the names of its varieties, sapphire and ruby, holds a pre-eminent position among coloured gem-stones. The barbaric splendour of ruby (Plate I, Fig. 13) and the glorious hue of sapphire are unsurpassed, and it is remarkable that […]

(1) HOPE The largest of coloured diamonds, the Hope, weighs 44 1/8 carats, and has a steely- or greenish blue, and not the royal-blue colour of the glass models supposed to represent it. It is believed to be a portion of a drop-form stone (dun beau violet) which was said to have been found at […]

THE number of diamonds which exceed a hundred carats in weight when cut is very limited. Their extreme costliness renders them something more than mere ornaments ; in a condensed and portable form they represent great wealth and all the potentiality for good or ill thereby entailed, and have played no small, if sinister, role […]

THE whole of the diamonds known in ancient times were 0btained from the so-called Golconda mines in India. Golconda itself, now a deserted fortress near Hyderabad, was merely the mart where the diamonds were bought and sold. The diamond-bearing district actually spread over a wide area on the eastern side of the Deccan, ex-tending from […]

ALTHOUGH none of the substances considered in this chapter come within the strict definition of a stone, since they are directly the result of living agency, yet pearl at least cannot be denied the title of a gem. Both pearl and coral contain calcium carbonate in one or other of its crystallized forms, and both […]

FLUOR, LAPIS LAZULI, SODALITE, VIOLANE, RHODONITE, AZURITE, MALACHITE, THULITE, MARBLE, APOPHYLLITE, CHRYSOCOLLA, STEATITE OR SOAPSTONE, MEERSCHAUM, SERPENTINE SPACE will not permit of more than a few words concerning the more prominent of the numerous mineral species which are employed for ornamental purposes in articles of virtu or in architecture, but which for various reasons cannot […]

TWO forms of natural glass have been employed for ornamental purposes. Obsidian results from the solidification without crystallization of lava, and corresponds in composition to a granite. The structure is seldom clear and transparent, and usually contains inclusions or streaks. The colour is in the mass jet-black, but smoky in thin fragments, and occasionally greenish. […]