All About the Making of Artificial Rubies and Sapphires

Far different from the imitation of gems is the making of them by artificial means, with the result of a real gem that is but slightly distinguished from those produced in Nature's laboratory. Although there are distinctions discernible to the expert with the aid of the magnifying glass, the gem stones thus produced-that are worthy of notice-contain the same component parts in their proportions that the natural stones do, and equal them in the principal characteristics of hardness, specific gravity, and refractiveness.

To quote Wirt Tassin:

A sharp distinction is to be drawn between the imitation of a gem stone and its formation by artificial methods. The imitation gem only simulates the natural substance; the artificial gem is identical with it in all its chemical and physical properties. Until recently the laboratory gem was hardly more than a curiosity, although its synthesis has undoubtedly been of value from the theoretical standpoint. Examples of this class are to be found in the diamond as produced by Moissan in the electric furnace and the synthesis of spinel and chrysoberyl by Ebelmen from mixtures of alumina and glucina, respectively, using boric acid at very high temperature as a solvent. Hydrofluoric acid and silicon fluoride have also been used to induce combination between silica and other oxides. In this manner topaz, a complex fluo-silicate, has been made by the action of fluoride of silicon upon alumina.

The minerals thus formed have usually been very small and of no commercial value. Quite recently, however, rubies have been produced by the fusion of alumina with a trace of chromium oxide in the electric furnace, and the art has progressed to such an extent that the product is now on the market for sale as watch jewels. The electric furnace has also produced another product which, while strictly speaking not a synthetic gem, yet is essentially an artificial one. Imperfect rubies, chips, and small stones, are fused in the furnace together with the addition of a small amount of colouring oxide such as chromium. The fused product is then cut and polished, and the result is a ruby of good colour and of fairly large size. Emeralds and other coloured stones have been made in the same way, and so promising has the industry become that the courts have been called upon to decide what constitutes a ruby. Their decision was in substance that the word ruby could be legally applied only to the red-coloured corundum, anhydrous oxide of aluminum, occurring ready formed in nature.

Reconstructed rubies however are in the main rightly placed and justly valued, for they are generally used in large quantities for medium-priced jewelry.

The French chemists Fremy and Verneuil have succeeded in manufacturing true gems, rubies chiefly, but also sapphires, by artificial processes. A title given to gems created by this or similar processes by man is "scientific" ruby, emerald, sapphire, or whatever the gem may be. Mr. Rudolph Oblatt of New York is an American producer of the "reconstructed" ruby, which has attained some commercial success, and its effect upon the market for rubies, whether this be considered desirable or otherwise, has been to lower the price of natural rubies because the demand has been lessened for them; this applying probably only to stones of one carat or less. When "reconstructed rubies" were first offered to the jewelry trade in Paris, and subsequently in the United States, their makers encountered many disheartening rebuffs; to-day many merchants and manufacturers who at first were horrified by, and who resented the suggestion of using the "reconstructed ruby," are complacently handling them in a continually increasing market for medium grade jewelry.

Mr. Oblatt describes his process as follows:

From the small genuine particles of ruby or "ruby sand" found with the real rubies in Burma I select pieces that are alike in colour and qualities; one of these chips I place upon the top of a "U"-shaped platinum iridium tube. Upon this is focussed the heat from two jets of oxygen and hydrogen gas--for the latter can usually be substituted gas from the street mains, as it contains a sufficient proportion of hydrogen gas to qualify it for this use--with a pressure of eight hundred pounds to the inch, producing a temperature of six thousand degrees F. As soon as the first chip is melted I introduce into the flame at the end of an iridium holder a second chip, which when it melts flies off and adheres to the first melted chip and they are fused together. The continuation of this process of adding particles results in the production of a genuine ruby of the shape of a pear, resting on its stem--the first chips fused--varying from five to ten carats in weight. The operation lasts from one to two hours, according to the size of the stone produced. The most difficult part of the process is the cooling; Nature's laboratory in which the ruby was produced had the resources of a tremendous sustained heat and a cooling process of unknown duration. In general, Nature's cooling process was too rapid, the evidence being in the minute cracks, called ribbons, which run through most rubies and the absence of which makes the perfect ruby one of the rarest and costliest of stones, especially when the cut gem weighs two carats or more. The cooling process is secret and one of the most important factors in the achievement of the reconstructed ruby. The enlarged ruby is then cut by the lapidary exactly as is the natural ruby, for it is the same in its chemical and physical constitution. This is attested by analysis made by very high scientific authorities, their reports being in my possession and open to the inspection of anyone.

The scientific ruby is wholly the result of artificial means but is genuine to the extent of being a properly proportioned combination of the chemical constituents of the natural ruby; in manufacturing the scientific ruby we begin with a solution of common alum, to which a trace of chrome alum is added as the ultimate colouring constituent. Now add ammonia, and there results a gelatinous precipitate of the hydrates of aluminum and chromium. This gelatinous precipitate is filtered off, evaporated down to dryness, and subsequently calcined into an intimate mixture of alumina and the oxide of chromium. It is then ground into an impalpable powder, and placed in the transforming apparatus. Through a tube passes a supply of coal-gas, through another tube a supply of oxygen. The two meet where they are ignited, and constitute a carefully regulated flame whose temperature is practically two thousand degrees. In a box at the top, is placed the powdered alumina, and the bottom of this box consists of a fine sieve. A small automatic tapper carefully jars the powder through the sieve and through a tube, which serves for the supply of oxygen. It thus happens that every trace of the powder must pass through the flames of two thousand degrees.

In a critical review of this process and its results, a very high scientific authority stated that:

These properties agree exactly with those of the natural ruby; but there is one feature by which these stones could be recognised as having been artificially produced; and that is by the form of the cavities existing in them, these being always spherical. The cavities in a natural ruby are always of an irregular form, and this would always afford a means of detecting the artificial stone.

The stones are rubies and are not imitations, as so many of their predecessors have been. But they are not natural rubies, even although produced from clippings of the same, since the crystalline growth is a new one after the clippings have been fused.

The sapphire as well as its sister of the corundum family, the ruby, has for years been the object of solicitude on the part of scientific experimentalists, who would produce real sapphires by artificial means; Mr. A. H. Petereit, of New York City, the well-known dealer in gems and gem minerals, who purveys rarities in this line to collectors the world over, and whose inventive genius is represented by more than twenty-five patents, exhibited to the author a "reconstructed sapphire" which, tested merely by a visual examination, rivalled natural sapphires, that of the same colour and purity would be very costly gems. Mr. Petereit's process is secret, and he modestly claims success only to the degree of producing stones of a size that will cut into small gems. Of the Petereit sapphires The Mineral Collector says:

We are pleased to announce that the honour has fallen to an American to at last manufacture a real reconstructed sapphire; successful in hardness, colour, brilliancy, and transparency. Efforts have been made in France, Germany, and other countries to successfully make blue sapphires, and, although they have been successful up to the cooling point, they always lost their colour and became gray when cool.

Mr. A. H. Petereit has had a German chemist working on a formula of his own for two years past, and has had his efforts at last crowned with success. At a meeting of experts in the gem business the reconstructed sapphires were placed among the real stones and they had to admit they were equal if not superior to the real gems.

When Mr. Petereit took up the mineral business his inventive mind was turned into a new channel, the manufacture of artificial gems. Already stories were being told of great successes accomplished in this line, but when it came to produce the stones they failed in one form or another; either the colour or hardness was wanting.

The new sapphires he has invented are perfect in every way. The cannot be scratched by the natural sapphire, they have a beautiful deep blue colour, their brilliancy is only equalled by the diamond, their specific gravity is exactly the same as the natural stone.

His success with scientific rubies was due to the fact that those he handled were the best in the market. They were made from small natural stones by a secret process and not from aluminum and other chemicals, as many now on the market were.

The Deutsche Goldschmiede Zeitung, a German jewelry trade journal, has supplemented an article, from which we quote, published upon the points of difference between reconstructed and genuine rubies, by presenting some additional facts, and especially by reproducing two illustrations made from enlarged photographs of reconstructed and genuine rubies supplied by A. F. Kotler, of St. Petersburg:

On careful examination, in the case of the artificial ruby, we notice at once the typical concentric lines as well as the little bubbles occurring in large numbers, which are always spherical, having, in other words, the character of an air bubble in a melted mass. The concentric fine lines, showing variations in the colour, were compared at the time with the circular or spiral lines that result from the string of a paste-like mass, leaving nothing to be desired as far as plainness is concerned. A naturally formed genuine ruby also shows spaces or enclosures, but these are more or less angular, being bounded by crystalline surfaces, The angularity of these voids is, moreover, determined by the entire crystalline structure of the natural stone.

If, therefore, in the genuine ruby, the colour is unequally distributed, the colour stripes invariably assume a vertical direction, are never concentric as in the artificial stone. We may also frequently note that the colour does not run in one direction, but that colour stripes, often of varying intensity, cross one another at obtuse angles; in other words, correspond strictly with the crystalline structure of the grown stone. We may reiterate the assertion that in a genuine natural ruby concentric lines are never noted. This most important, and at the same time certain and simplest, distinguishing characteristic, is the more to be regarded, inasmuch as the specific gravity, the colour, the hardness, and the dichroism--in other words, all the optical and chemical properties--of the artificial ruby correspond, more or less, with those of the genuine stone and consequently the scientific assistance, in this case, fails us entirely. An experienced gem expert will, moreover, recognise the genuine ruby by its peculiar, characteristic, soft, silky brilliance, which is lacking in all artificial rubies.

At the recent convention of German jewellers in Heidelberg, where the question as to the nature of the so-called artificial or "scientific" precious stones was exhaustively discussed and a resolution expressing an attitude of opposition towards excessive advertisement of these productions was adopted, Court Jeweller Th. Heiden, in the name of the "Association of Jewellers, Gold and Silversmiths of Bavaria," spoke in favour of hearing an opinion of a prominent authority in regard to the entire subject. According to the Journal der Goldschmiedekunst, this has now been rendered, the well-known mineralogist Prof. Dr. Conrad Oebbeke, of the technical high school in Munich, having expressed himself as follows, concerning artificial precious stones: