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Geoarchaeology and Archaeomineralogy (Eds. R. I. Kostov, B. Gaydarska, M. Gurova). 2008. Proceedings of the International Conference, 29-30 October 2008 Sofia, Publishing House “St. Ivan Rilski”, Sofia, 98-102.

THE CHALLENGES FACING THE DIAMOND EDGE IN ITS CONTACT WITH THE PRECIOUS STONE WHEN ENGRAVING GEMS (INTAGLIOS AND CAMEOS) Stephan Lazarov

“St. Cyril and St. Methodius” University of Veliko Turnovo, 2 T. Turnovski Str., 5003 Veliko Turnovo

ABSTRACT. I will try to share my personal professional experience as an artist who has been doing glyptic art professionally for over 20 years. Glyptic art is exceptionally rare, costly and difficult art since the high hardness of the precious stone makes gems unique, and mistakes are therefore unforgivable. Few are the artists worldwide today who have are brave enough to revive that ancient and forgotten art, dating back 6000 years ago, whose technology has been kept in deep secrecy.

It is well known that the first drawings on rock surface and horn have been engraved with a flint edge. But when the flint surface came to be used as ‘picture surface’ (depiction field), the big mystery arises, the question to which no scholar or scientist has given an unambiguous answer so far – what edge has been used for engraving the flint chunks of the unique finds from 30000 years BC. ‘Northern Deer’ in Grimes Graves near Brandon or Ox in profile in the Peche Marlene cave. What edge harder than flint was used to engrave those drawings? The mysterious drawings on the ‘Ica stones’ in Peru are thought to have been engraved with an obsidian edge. But flint is harder than obsidian which, too, was used for making cutting and drilling implements in antiquity. An edge capable of engraving the flint’s hard surface could only be of some kind of crystal harder than flint (7 on the Mohs’s scale). Crystals of this kind are: diamond in the first place, the hardest substance found in nature (10 on the Mohs’s scale); corundum (varieties – ruby and sapphire with hardness 9 on the Mohs’s scale); chrysoberyl (alexandrite or cymophane with hardness 8-8.5 on Mohs’s scale) or topaz – 8 on the Mohs’s scale of hardness. The drawings on the stone are most likely to have been engraved with some of these crystals of high hardness. These examples allow us to assume that these are the prehistoric man’s first steps towards the art of engraving precious stones. However, I would like to specify something: the article focuses only on stones of high hardness, that is to say precious stones, and I prefer the classic names of intaglios and cameos. It is also understandable that the term ‘precious stone’ is used more frequently, rather than the new definition ‘precious mineral’ because the author is a sculptor. I am not going to expand on things that are well known about the properties and processing of precious stones either, as there is ample literature on that. I will try to explain certain problems related mostly to engraving gems (intaglios and cameos).

Before that I will share my views about some statements related to the technique of grinding and drilling precious stones. In the treasures of the Varna Chalcolithic necropolis, apart from the gold objects, what also impress are the necklaces of chalcedony beads – carnelian and sard, shaped like polyhedral doubly intersected pyramids with well ground and polished walls, whose number in of the some beads reaches 32. No scientific explanation has been given so far as to how and what abrasives have been used in the processing of chalcedony which is harder than tempered steel. The assumption by some modern researchers that the abrasive material is quartz sand (or crushed flint), to me at least, are rather unconvincing because quartz and flint have the same hardness as chalcedony – 7 on the Mohs’s scale. It is even more paradoxal if we accept that these beads have been drilled with a small flint edge, providing their holes are less than 1 mm across. When I personally saw and touched these necklaces, stored at the Varna Archaeological Museum, I assumed that the so called Naxos stone, known to ancient gem masters as far back as the Crete-Mycenaean civilization, was used as an abrasive for grinding and polishing. This Naxos stone, extracted from natural rocks, contains corundum grains which are harder than quartz and flint and is much closer to diamond in terms of hardness. The drilling may have been performed with a thin copper needle and a paste of a similar stone crushed to powder and mixed with water or fat, turned with a bow. This process was too slow to drill the hole of a single bead, 4-15 mm long. Chalcolithic needles like these are stored at the above mentioned museum. I think that the legend that the treadle lathe for engraving gems was invented by Theodoro of Samos and Roiko, another gem master of the Ionic period, should be called into question. The belt-treadle lathe, through the technique of spinning metal edge at the end of the needle, unlike the technique of engraving with an ordinary edge, suitable only for soft stones, made possible the production of gem seals from much harder

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costly minerals such as chalcedony, agate, jasper, sard, carnelian, garnet, amethyst, etc. The motion of the small wheel was transmitted by the large one – a type of spinning wheel, provided with an axis, to which a metal needle was attached, spinning at a high speed and periodically lubricated with abrasive powder mixed with oil. The images were cut very slowly on the surface of the stone, which was the base, and very often polished as smooth as mirror in advance. As is known, agate, as well as other stones used in glyptic art, is harder than steel which is why gems are made not with a metal edge but with abrasives made of Naxos stone, corundum or diamond powder. As the master was forced to engrave the stones ‘blindly’ in this way because the drawing was covered by the abrasive and oil mixture, the gems were made very slowly, after months and years of hard work. It is not a coincidence that one of the best glyptic researchers at the beginning of the XX c., Babelon (1897), notes that it took as much time to do a large gem as it did to build a whole temple. To this effect is the legend of the notable gold ring seal belonging to Polycrates with an engraved emerald made by Theodoro of Samos which cost as much as the entire island of Samos. The principle is the same as with the technique of spinning metal edge at the end of the needle, the only difference being that instead of a round and transversally bevelled (cutting edge) of the spinning needle, the ancient Etruscans did their gems in the aglobolo style, where the metal needle ended with a ball with various diameters. In this way the details of the images have concave spherical shapes – expressive and attractive but above all, for decorative use because of the utilisation of only one type of edge – with a spherical shape. In my view the famous master Theodoro of Samos has most probably ‘rediscovered’ rather than invented the ‘engraving treadle lathe’. The time of the Samos tyrant Polycrates and the master engraver is 522 BC, and the same technique of spinning metal edge at the end of the needle was used for making the Mesopotamian cylindrical seals (IV-III mill. BC), as well as the Crete-Mycenaean gems in the II mill. BC. According to another statement by some researchers, the ancient sculptor engravers did not know or use magnifying lens. If the widespread story that Nero watched gladiator combats through a transparent crystal emerald lens and a large polished chrysolite can be interpreted as a legend as well, then each spherical convex or concave crystal item is in itself literally an ‘optical lens’. I assume that as far as ancient gems with very complex images are concerned, the ancient masters have used magnifying ‘lenses’ of transparent natural crystals, for example rock crystal which has superb optical properties. Otherwise it wouldn’t be possible to see with a naked eye the details of the images on many masterpieces of glyptic art such as Marcus Curtius from the III c. BC (Fig. 1), with the stunning miniature size of the horse and horseman on carnelian – 15x12 mm! It is hard to imagine how even with a threefold magnifying lens these miniature shapes were cut into the hard stone. Each artist would find it very difficult even if they only tried to draw with a pencil on paper the image of a horse and horseman of that size in an ellipse.

Fig. 1. Marcus Curtius – III c. BC (carnelian, 15x12 mm)

Regarding the use of glass magnifying lenses in antiquity, the outstanding scientist and astronomer abbot Moreau in his book The Secret Science of Pharaohs mentions the mysterious magnifying glass lens, found during excavations in Egypt, which after an expert examination turned out to be as old as five thousand years. Today it is known how the illustrious Egyptian glass, used as a magnifying lens for making miniature gems, without which those glyptic masterpieces with the most complex images would not have been created, came to life in the easiest and simplest way. Perhaps one of the most crucial evidence of that statement is the fact that lenses of rock crystal, dating back to 3800 BC were found during archaeological excavations in Nimrud, Mesopotamia. Regarding what is ‘known’ and what is ‘unknown’ about the technique and technology of glyptic art, I was able to find out through my personal practical experience that what is known today, is not everything, particularly as far as the creation of the best models of gems and cameos is concerned. What is more, no one can master the art of glyptic, sculpture or drawings solely from a book. The ancient masters have undoubtedly kept secret the major subtleties of their craft. Despite my view that they used a magnifying lens and a ‘technique on the clean’ (visible), and not only ‘technique on the blind’, known today and pointed out by some authors, to me the mystery remains as to whether the ancient masters used and knew something else which is still unknown to us. ‘Stones are speechless teachers, they make speechless those who watch them – whatever they learn from them, they share it with no one else’ – says Goethe. The major challenge of the precious stone is its resistance to scratching – hardness. It turns out to be its main attribute which has made the images in the stone surface eternal. Glyptic art – gems (intaglios and cameos) have remained intact for ages, so much so that in all their unique brilliance they seem as if they have just been created. The first challenge – hardness of minerals, the two benchmark tables by Mohs and Rosenwall are very popular. Based on the method of scratch, the table by the Viennese mineralogist Mohs is easy to apply but not used very often today because ground stones are damaged by the scratch. Rosenwall’s table is much more precise than that of Mohs because it allows calculating how many times one mineral is harder than another, depending on the technique of grinding.

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In my long-standing practice of engraving precious stones, I have composed a comparative Table N3а, which I use today (Table 1). It combines both the Mohs’s and Rosenwall’s tables, preserving the digital numeration of the softest mineral – talc is 1 on the Mohs’s scale instead of 0.03 on the Rosenwall’s scale, and the qualities of the absolute grinding hardness. In this way the differences between the benchmark minerals and talc can be seen better. Thus from Table 3, we can see that diamond (10 on the Mohs’s scale) is harder than talc not 10 but 4666666 times; 140 times harder than corundum (ruby and sapphire), 1166 times harder than quartz, (amethyst, citrine, morion, rock crystal, etc.) because numeration in Mohs’s table (1-10) determines the order of minerals, and not the exact correlation between their absolute grinding hardness. On the basis of Table 3a, through simple arithmetic calculation I composed a more complete Table 3b of the hardness of the same key minerals (from talc to diamond), from which we can see exactly the differences between these minerals. For example, corundum is 8.3 times harder than quartz; quartz is 26.6 times harder than calcite; topaz is only 1.45 times harder than quartz! Although Mohs’s table is easier to apply in practical mineralogy, I think that for glyptic art the option which I propose, and which is published for the first time, is more useful since it combines Mohs’s practicality and Rosenwall’s accuracy. From what has been written so far, it is clear that hardness is tackled by hardness, and the best tools are the diamond tools, and they are very expensive. The second challenge – the miniature size, concerns not only the precious stone, but also the engraved gem (intaglio or cameo). Along with the high hardness of the costly material the master should also deal with the gem’s small surface (polished

as smooth as a mirror) over which a smaller image is cut – a head portrait, figure or composition of several figures, which are placed on a surface of 1-2 cm2. Yet, the gem’s miniature size is not much of an issue when the cut refers to engraving a purely symbolical and geometrical, schematic and stylized image with simple details and identical depth of the grooves. However, it is another matter when it comes to gems with a high degree of complexity of multilayer relief image and rich nuances between the various perspectives in depth. A lot of theoretical and practical experience is needed here for this kind of engraving, as well as knowledge of the grinding techniques and smooth and brilliant engraving. A wonderful example from antiquity is the gem of the figure of Mark Curtius, on a surface of 1.8 cm2. The third challenge of the gem intaglios concerns the ‘inverse’ (mirror) image of their negative relief image. The deeper it is engraved into the stone, the more salient will be the relief positive imprint, that is, the seal bas-relief itself. The contact with the precious stone has been felt particularly strongly by A. E. Fersman who writes that ‘this contact can only make him an artist burning in the fire of inspiration’. As we already mentioned, three are the challenges that the diamond edge has to tackle, guided by the artist’s hand in the creation of the image on the costly stone: high hardness, miniature size and ‘internal space’. To deal with the hardness we need to possess rotating diamond ‘edges’ of various size and shape. The experience of operating these tools on the miniature surface is crucial as it allows the artist to obtain a professional ‘feeling of the stone’. The ability to ‘see’ the shape inside is crucial when making gems intaglios. I have solved each of the problems by many experiments and many doubts.

Table 1. Important minerals for determining hardness 3а

Key mineral Manner of scratching Hardness on Mohs, Table N1

Hardness on Rosenwall, Table N2

Comparative scale, Table N3а

talc with a nail 1 0.03 1 gypsum with a nail 2 1.25 41 calcite with a copper needle 3 4.5 150 fluorite with a knife 4 5.0 166 apatite with a knife 5 6.5 216

orthoclase with a steel needle 6 37.0 1233 quartz scratches glass 7 120.0 4000 topaz scratches glass 8 175 5833

corundum scratches glass 9 1000 33333 diamond scratches glass 10 40000 4666666

Table 2. Detailed table of hardness of minerals 3b

10 diamond 1 - - - - - - - - - 9 corundum 140 1 - - - - - - - - 8 topaz 800 5.7 1 - - - - - - - 7 quartz 1166 8.3 1.45 1 - - - - - - 6 orthoclase 3784 27 7.7 3.24 1 - - - - - 5 apatite 21605 154 27 18.5 5 1 - - - - 4 fluorite 28112 201 35 24.1 7.43 1.3 1 - - - 3 calcite 31111 222 38.9 26.6 8.22 1.44 1.1 1 - - 2 gypsum 113821 813 139 97.5 30 5.26 4 3.66 1 - 1 talc 4666666 33333 5833 4000 123 216 166 150 41 1

mineral diamond corundum topaz quartz orthoclase apatite fluorite calcite gypsum talc

10 9 8 7 6 5 4 3 2 1

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I realized through experience that for gems with the most complex images, the ancient masters used – abrasive ‘edges’, allowing thin finesse of the image. My hypothesis on this issue is based on several facts: there are periods of boom and decline in the history of world glyptic art; the secrets of the technique were transmitted only between those initiated in the temple and royal workshops, ‘from father to son’, and each master added something to what they had learned, which was later forgotten for many generations to come; each gem mirrors ‘the way’ in which it was created. The ‘steps’ of the edge can be traced on the surface of the image! The negative concave form suggests the shape, size and the grainy texture of the spinning ‘edge’ author’s thought, his ‘feeling for the stone’. That is why I assume that the precise technique was accessible to few glyptic masters. To me personally, trying to find out whether it is possible to engrave a human figure on such a small composition surface, with precise multilayer depth of the relief (1-1.5 cm2), with the diamond edges I have made myself, has been a real challenge. I think I have succeeded but I will leave it to the connoisseurs to judge. As an example I can point the gem of ‘Flying fairy’ (Fig. 2).

Fig. 2. ‘Flying fairy’ (chalcedony, 16x11 mm)

The semi-naked mythical figure fills freely the ‘living composition field – ‘the sky’, with the freely flying body (and soul). The word for fairy in Bulgarian means will and freedom, so that is a creature which is a symbol of freedom. Freedom – flying in her own ‘space’ – personification of the soul (with or without ‘visible’ wings – she flies freely). Semi-visible, semi-invisible penetrated by the light of chalcedony, the fairy figure ‘breaks’ the tranquil space of the background with the dynamism of her flight. I engraved the gem with about 27 types of rotating tools. But the magic of portrait gems remains unique and they hold a prestigious position in art, both in the most ancient civilizations and today. Portrait gems were made back in antiquity for Alexander the Great, Nero, Octavian, Caesar and others by the best masters of gems which possessed extremely high artistic value (Fig. 3). This explains to some extent why the eminent master of glyptic art Pirgotelius was the only engraver to whom Alexander the Great allowed the have his image engraved on a gem. The ruler of Egypt, Cleopatra presented her most notable guests with an image of herself engraved on a gem. Unlike other countries, mostly in Europe, in Bulgaria till the National Upraise and after it there is no evidence for local master engravers making portrait gems.

Fig. 3. Portrait of Claudius (amethyst, 17x14 mm)

Portrait glyptic art is exceptionally rare phenomenon in modern art today (Lazarov, 2005) not only in Europe but also across the world (Fig. 4-5). Ancient imitations are not considered. When engraving a concrete portrait, and not just an image in general, a high degree of creative remembering is required in order to reproduce the image ‘by memory’, it must have been ‘embedded’ in the artist’s mind. This supreme stage of perception and reproduction cannot always be achieved. This state of the human spirit is similar to the autosuggestion of the legendary archers of the East who perceive the target from a long distance as a purpose which is ‘inside them’. Or as the ancient Eastern sagas have said: ‘feel the object inside yourself’!

Fig. 4. Rock crystal for the image of the outstanding Bulgarian portrait artist Vladimir Dimitrov the Master (25x16 mm) Fig. 5. Bulgarian writer and satirist Radoi Ralin (obsidian, 22x14 mm)

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I decided that this stone is the most appropriate one for the Master (Vladimir Dimitrov the Master), known for the purity and wealth of his spirit, a bright image in the Bulgarian art of drawing and painting. The rock crystal possesses wonderful qualities – purity, hardness and transparency. The ellipse composition field is in living shape with dimensions 25x16 mm. The profile fills harmoniously the entire space of the crystal, and the general layout of the image – face, hair and clothes associate the shape of ‘flame’ without unnecessary attributes getting in the way of the clear silhouette. To keep the gems from accidental scratches, the idea of ‘hidden image’ occurred to me, that is how the negative relief image could become ‘visible’ without the artist having to make imprints and moulds. This was possible in only one way – to view the image on the gem in a way that allows the light to penetrate it from inside, which could happen only with transparent stones such as crystals. Viewed ‘contra-jour’, the concave image seems convex and emits in a particularly sacred way the light rays penetrating the crystal. A similar impact of this phenomenon can be achieved when we place the transparent-crystal gem on a polished 20-22 carat gold chip which is resistant to

chemicals and is not oxygenated in air or water. The gem thus placed shines with a special light since the rays pass through the transparent crystal, reflected by the surface of the gold base and pass again through the concave image rendering it a new look – as convex or positive relief, giving complete idea of the real shape. The gem has already combined the wonderful optical properties of the natural crystal, developed by the light and receiving the spirituality of the image incarnated in the stone in the trinity – stone, light and spirit. These two major advantages show the gem intaglios in a newer light, as an independent work of art of the most miniature sculpture made on a precious stone.

References Babelon, M. E. 1897. Catalogue des camées antiques et

modernes de la Bibliothèque Nationale. E. Leroux, Paris, 463 p.

Lazarov, S. 2005. Regal Art. Bulgarski Hudozhnik, Sofia, 171 p. (in Bulgarian)