George Frederick Herbert Smith

“ When the love-sick Juliet queried ‘What’s in a name?’ her mind was wandering far from jewels; for them a name is everything. The beautiful red stones that accompany the diamond in South Africa were almost a drug in the market under their proper title—garnet, but command a ready sale under the misnomer ‘Cape-ruby.’ To many minds there is a subtle satisfaction in the possession of a stone which is assumed to be a sort of ruby that would be destroyed by the knowledge that the stone really belonged to the cinderella species of gem-stones—the despised garnet. ”

“ FASHIONING OF GEM-STONES ALTHOUGH many of the gem-stones have been endowed by nature with brilliant lustrous faces and display scintillating reflections from their surfaces, yet their form is never such as to reveal to full perfection the optical qualities upon which their charm depends. ”

“ Not many years ago, for instance, violet was the favourite colour for ladies’ dresses, and consequently amethysts were much worn to match, but with the change of fashion they speedily sank to their former obscurity. Another stone may perhaps figure at some royal wedding; for a brief while it becomes the vogue, and afterwards is seldom seen.
Except that diamond, ruby, emerald, and sapphire, and, we should add, pearl, may indisputably be considered to occupy the first rank, it is impossible to form the gem-stones in any strict order. Every generation sees some change. ”

“ The colour is the least reliable character that may be employed for the identification of a stone, since it varies considerably in the same species, and often results from the admixture of some metallic oxide, which has no essential part in the chemical composition and is present in such minute quantities as to be almost imperceptible by analysis. Who would, for instance, imagine from their appearance that stones so markedly diverse in hue as ruby and sapphire were really varieties of the same species, corundum? ”

“ That a gem-stone should be a delight to the eye is a truism that need not be laboured; for such is its whole raison d’être. The members of the Mineral Kingdom that find service in jewellery may be divided into three groups, according as they are transparent, translucent, or opaque. Of these the first, which is by far the largest and the most important, may itself be further sub-divided into two sections: stones which are devoid of colour, and stones which are tinted. ”

“ Moreover, the natural faces are seldom perfect; as a rule the stones are broken either through some convulsion of the earth’s crust or in course of extraction from the matrix in which they have lain, or they are roughened by attrition against matter of greater hardness, or worn by the prolonged action of water, or etched by solvents. Beautiful octahedra of diamond or spinel have been mounted without further embellishment, but even their appearance might have been much improved at the lapidary’s hands. ”

“ GARNET THE important group of minerals which are known under the general name of garnet provides an apt illustration of the fact that rarity is an essential condition if a stone is to be accounted precious. Owing to the large quantity of Bohemian garnets, of a not very attractive shade of yellowish red, that have been literally poured upon the market during the past half-century the species has become associated with cheap and often ineffective jewellery, and has acquired a stigma which completely prevents its attaining any popularity with those professing a nice taste in gem-stones. ”

“ The history of the famous stone called the Koh-i-nor, meaning Mound of Light, is known as far back as the year 1304, when it fell into the hands of the Mogul emperors, and legend even traces it back some four thousand years previously. It remained at Delhi until the invasion of North-West India by Nadir Shah in 1739, when it passed together with an immense amount of spoil into the hands of the conqueror. At his death the empire which he had so strenuously founded fell to pieces, and the great diamond after many vicissitudes came into the possession of Runjit Singh at Lahore. ”

“ The ugly yellowish tint given by the extraordinary ray of sapphire should be avoided by cutting the stone with its table-facet at right angles to the prism edge, which is the direction of single refraction. Whether a ruby should be treated in the same way is a moot point. No doubt if the colour is deep, it is the best plan, because the amount of absorption of light is thereby sensibly reduced, but otherwise the delightful nuances distinguishing ruby are best secured by cutting the table-facet parallel to the direction of single refraction. ”

“ The factors that govern the properties of a brilliant-cut stone are large colour-dispersion, high refraction, and freedom from any trace of intrinsic colour. The only gem-stone that can vie with diamond in these respects is zircon. ”

“ A careful eye will perceive that the coloured shadow-edge is in reality a spectrum, of which the violet end lies in the dark portion of the field and the red edge merges into the bright portion. The yellow colour of a sodium flame, which, as has already been stated, is selected as the standard for the measurement of refractive indices, lies between the green and the red, and the part of the spectrum to be noted is at the bottom of the green, and practically, therefore, at the bottom of the shadow, because the yellow and red are almost lost in the brightness of the lower portion of the field. ”

“ A rough diamond, especially from river gravels, has often a peculiar greasy appearance, and is no more attractive to the eye than a piece of washing-soda. It is therefore easy to understand why the Persians in the thirteenth century placed the pearl, ruby, emerald, and even peridot before it, and writers in the Middle Ages frequently esteemed it below emerald and ruby. The Indian lapidaries, who were the first to realize that diamond could be ground with its own powder, discovered what a wonderful difference the removal of the skin makes in the appearance of a stone. ”

“ The colours that are most admired—the fiery red of ruby, the royal blue of sapphire, the verdant green of emerald, and the golden yellow of topaz—are pure tints, and the absorption spectra corresponding to them are on the whole continuous and often restricted. They therefore retain the purity of their colour even in artificial light, though certain sapphires transmit a relatively larger amount of red,3 and consequently turn purple at night. Of the small group of translucent stones which pass light, but are not clear enough to be seen through, the most important is opal. ”

“ CHALCEDONY, AGATE, ETC. CHALCEDONY and agate, and their endless varieties, are composed mainly of silica, but the separate individual crystals are so small as to be invisible to the unaided eyesight, and occasionally are so extremely minute that the structure is almost amorphous. The colour and appearance vary greatly, depending upon the impurities contained in the stone, and, since both have been made a criterion for differentiation of types, a host of names have come into use, none of which are susceptible of strict definition. ”

“ Ordinary dust is largely composed of grains of sand, which is quartz in a minute form, and a gem-stone should therefore be at least as hard as that. Paste imitations are little harder than 5, and consequently, as experience shows, their polish does not survive a few weeks’ wear. Hardness is, however, of little use as a discriminative test except for distinguishing between topaz or harder stone and paste. Diamond is so much harder than other stones that it will leave a cut in glass quite different from the scratch of even corundum. ”

“ REFLECTION, REFRACTION, AND DISPERSION IT is obvious that, since a stone suitable for ornamental use must appeal to the eye, its most important characters are those which depend upon light; indeed, the whole art of the lapidary consists in shaping it in such a way as to show these qualities to the best advantage. ”

“ It is evidently desirable that any stones used in jewellery should be able to resist the mechanical and chemical actions of everyday life. No one is anxious to replace jewels every few years, and the most valuable stones are expected to endure for all time. The mechanical abrasion is caused by the minute grains of sand that are contained in ordinary dust, and gem-stones should be at least as hard as they—a condition fulfilled by all the principal species with the exception of opal, turquoise, peridot, and demantoid. ”

“ In bygone days when despotic government was universal, the possession of a splendid jewel in weak hands but too often precipitated the aggression of a greedy and powerful neighbour, and plunged whole countries into the horrors of a ruthless and bloody war. In more civilized days a great diamond has often been pledged as security for money to replenish an empty treasury in times of stress. ”

“ No difference at all will be shown in directions in which a stone is singly refractive, and it is therefore always advisable to examine a stone in more than one direction lest the first happens to be one of single refraction. For determinative purposes it is not necessary to note the exact shades of tint of the twin colours, because they vary with the inherent colour of the stone, and are therefore not constant for the same species; we need only observe, when the stone is tested with the dichroscope, whether there is any variation of colour, and, if so, its strength. ”

“ Recent years have witnessed many changes in the jewellery world. Gem-stones are no longer entirely drawn from a few well-marked mineral species, which are, on the whole, easily distinguishable from one another, and it becomes increasingly difficult for even the most experienced eye to recognize a cut stone with unerring certainty. ”

“ Diamond is by far the hardest substance in nature, being marked 10 in Mohs’s scale of hardness, but it varies in itself; stones from Borneo and New South Wales are so perceptibly harder than those usually in the lapidaries’ hands, that they can be cut only with their own and not ordinary diamond powder, and some difficulty was experienced in cutting them when they first came into the market. ”

“ When pure, it is colourless; the splendid tints which are its glory have their origin in the minute traces of the other oxides present. No doubt chromic oxide is the cause of the ruddy hue of ruby, since it is possible, as explained above (p. 117) , closely to imitate the ruby tint by this means, but nothing approaching so large a percentage as 21⁄2 has been detected in a natural stone. The blue colour of sapphire may be due to titanic oxide, and ferric oxide may be responsible for the yellow hue of the ‘oriental topaz,’ as the yellow corundum is termed. ”

“ SPINEL
(Balas-Ruby, Rubicelle) 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 very similar to the true ruby in appearance; they are probably often confused, especially since they are found in intimate association in nature. ”

“ What is the relative amount of reflected light depends upon the nature of the stone—its refractivity and hardness—and determines its lustre; the greater the amount the more lustrous will the stone appear. There are different kinds of lustre, and the intensity of each depends on the polish of the surface. From a dull, i.e. an uneven, surface the reflected light is scattered, and there are no brilliant reflections. All gem-stones take a good polish, and have therefore, so long as the surface retains its polish, considerable brilliancy ”

“ The cut stone will therefore have not only the density and hardness, but also all the optical characters—refractivity, double refraction,120 dichroism, etc.—pertaining to the natural species, and will obey precisely the same tests with the refractometer and the dichroscope. Were it not for certain imperfections it would be impossible to distinguish between the stones formed in Nature’s vast workshop and those produced within the confines of a laboratory. The artificial stones, however, are rarely, if ever, free from minute air-bubbles (Fig. 55) , which can easily be seen with an ordinary lens. ”

“ Great, therefore, was the consternation and the turmoil when concrete evidence that could not be gainsaid showed that man’s restless efforts to bridle nature to his will were not in vain, and congresses of all the high-priests of jewellery were hastily convened to ban such unrighteous products, with what ultimate success remains to be seen. ”

“ It is usual to say that iron is heavier than wood, but the statement is misleading, because it would be possible by selecting a large enough piece of wood to find one at least as heavy as a particular piece of iron. We have, in fact, to compare equal volumes of the two substances, and all ambiguity is removed if we speak of relative density or specific gravity—the former term being usually applied to liquids and the latter to solids—instead of weight or heaviness. The density of water at 4° C. is taken as unity, that being the temperature at which it is highest ”

“ The finest cat’s-eyes are found in India and Ceylon, and are high in favour with the natives. Greenish stones of an inferior quality are brought from the Fichtelgebirge in Bavaria, and are sold as ‘Hungarian cat’s-eyes,’ despite the fact that no such stone occurs in Hungary—another instance of jewellers’ disdain for accuracy. Tiger’s-eye occurs in considerable quantity in the neighbourhood of Griquatown, Griqualand West, South Africa. A silicified crocidolite, in which the blue colour is retained, comes also from Salzburg, and is known as sapphire- or azure-quartz, or siderite. ”

“ If it be moved towards the observer from the further end, a misty shadow appears to move down the scale until the correct position is reached, when the edges spring into view.
Any facet of a stone may be utilized so long as it is flat, but the table-facet is the most convenient, because it is usually the largest, and it is available even when the stone is mounted. That the stone need not be removed from its setting is one of the great advantages of this method. The smaller the stone the more difficult it is to manipulate ”

“ It is very important that the claw setting be periodically examined, lest the owner one day experience the mortification of finding that a valuable stone has dropped out; gold, owing to its softness, wears away in course of time.
Up to quite recent years modern jewellery was justly open to the criticism that it was lacking in variety, that little attempt was made to secure harmonious association in either the colour or the lustre of the gem-stones, and that the glitter of the gold mount was frequently far too obtrusive. ”

“ The tint must not be too light or too dark in shade: a stone that has barely any colour has little interest, and one which is too dark appears almost opaque and black. The lapidary can to some extent remedy these defects by cutting the former deep and the latter shallow. In certain curious stones—for instance tourmaline—the transparency, and in others—such as ruby, sapphire, and one of the recent additions to the gem world, kunzite—the colour, varies considerably in different directions. ”

“ HARDNESS AND CLEAVABILITY EVERY possessor of a diamond ring is aware that diamond easily scratches window-glass. If other stones were tried, it would be found that they also scratched glass, but not so readily, and, if the experiment were extended, it would be found that topaz scratches quartz, but is scratched by corundum, which in its turn yields to the all-powerful diamond. There is therefore considerable variation in the capacity of precious stones to resist abrasion, or, as it is usually termed, in their hardness. ”

“ The fashioning of coloured stones, as all the gem-stones apart from diamond are termed in the jewellery trade, is on account of their inferior hardness a far less tedious operation. They are easily slit, for which purpose a vertical wheel (Plate VIII) made of soft iron is used; it is charged with diamond dust and lubricated with oil, generally paraffin. When slit to the desired size, the stone is attached to a conveniently shaped holder by means of a cement, the consistency of which varies with the hardness of the stone. ”

“ It was then discovered that, despite the colour, the stones had the physical characters, not of sapphire, but of the species closely allied to it, namely, spinel, aluminate of magnesium. By an unsurpassable effort of nomenclature these blue stones were given the extraordinary name of ‘Hope sapphire,’ from fanciful analogy with the famous blue diamond which was once the pride of the Hope collection. A blue spinel is occasionally found in nature, but the actual tint is somewhat different. These manufactured stones have the disadvantage of turning purple in artificial light. ”