Type Ha provides the purest diamonds, which contain no nitrogen and thus are completely colorless. When manganese is present as a trace element a rose-pink color results (as in the Regent and the Williamson). Type lib is characterized by slight traces of aluminium, which not only colors such diamonds blue (like the Hope and the Wittelsbach), but also turns them into semiconductors which are vital to the electronic industry.
The structural build of diamond engagement rings arouses our curiosity about the conditions of their formation. The interpretation prevailing today rests on the hypothesis that in a very early era there existed above the sima widespread focal points of magma in which dense olivine aggregates gradually became concentrated. In a second, much later period, basic magma masses were forced, under immense internal pressure, into fracture zones of the middle and upper crust, and alteration of the olivine aggregates into eclogite knolls came about.
These consist of olivine, garnet, and diopside diamond engagement rings . In the course of this unusual metamorphism, which took place at about 2 5 kilometers depth under an overburden pressure of about 50,000 atmospheres and at temperatures of about 1,300° C, the formation of diamonds occurred at the same time as that of other minerals. In a third phase the diamonds were catapulted in sporadic explosive eruptions from the earth's interior to its surface and embedded in the kimberlite rock which formed as the lava masses cooled. In the course of the last two hundred million years the friable kimberlite crumbled away through the destructive ravages of weathering.
The diamonds thus freed were in part set down in the detritus of river beds, and in part carried down to the sea coast and there deposited either in coastal sediments or in shoal banks in the ocean. As a result of this, the diamonds are won from very varying strata: from the primary rock fill of the volcanic necks (the "blue ground"), from the secondary gem gravels of the river beds, and from the marine beds of coastal sands.
Consequently, very distinct mining methods have been developed, ranging from highly mechanized operations in South Africa, Tanzania, and Siberia, through the most primitive excavation methods of private diggers in all parts of the world, to the imposing array of machine installation and earth moving along the coast of southwest Africa. In contrast to the primary deposits, where some 3.6 tons produce one carat of diamond rings (1:18 million), the ratio of the littoral mining areas in southwest Africa amounts to only 1:80 million (i.e. one carat of diamond from sixteen tons of spoil). Of the world's annual production of diamonds, which in 1967 totalled 42.4 million carats, only approximately 21 percent, or 9 million carats, were diamonds of gem quality.
Glassy and unattractive, shapeless and rough, diamonds can hardly be told from ordinary pebbles when, separated from their common brethren in their long treatment process, they at last arrive on the sorting table. Then man, with his knowledge and his
skill, transforms them into objects of lustrous life. Giving them a facet-rich cut brings their beauty to scintillating fruition, displays their clear transparency, and sparks their high intensity of light—that unique combination of optical properties which is described as brilliance. Brilliance is created by the combined effects of adamantine luster (reflection of light from the polished surface), high refraction of light (diamond engagement rings has a refractive index of 2.42, which means that light in diamond travels 2.42 times more slowly than in air), total reflection of the rays returned from the interior of the cut stone, dazzling fire of the light emerging from the stone dispersed into its component colors, and vivid sparkle. Diamond cutting is both science and art at one and the same time. The first stage is to establish the form by cleaving or, nowadays, principally by sawing on a very fine, circular metal saw. Depending on the size and the individual resistance, this can last hours or days. Before the two different sized parts can be cut into brilliants the cutter gives them a roughly circular form by rounding the pointed corners. For faceting and polishing, the rounded diamond, held in a dop, is lowered on to the quickly rotating cutting lap, which is coated with diamond powder and oil. During this most delicate phase of the cutting process the cutter sets down the diamond and lifts it up again hundreds of times in order to supervise his cut. But however carefully a diamond is cut, about half its weight is always lost in the process. Then, finally, after day- or week-long care, the diamond has become a brilliant-cut gem—a glittering jewel with its rich pattern of planes and geometrically shaped facets and the glistening play of light of its fiery brilliance. It is of unsurpassable beauty, arousing enraptured delight and astonished wonder.
Yet, however important the cutting is for the inimitable beauty of the brilliant-cut diamond, it is only one of the Four Cs, that is, carat, clarity, color, and cut, which together constitute the qualitative factors of the worth of a diamond. There is a widespread misconception among the public that a good diamond must be blue-white and flawlessly clear. Really blue-white diamonds are extremely rare, so rare indeed that many a diamond merchant has never encountered a blue-white diamond in his life. The subtle color nuances from blue-white through finest white, white, off-white, and yellowish to yellow apply only to the so-called white, i.e. colorless, group. The full-colored varieties are classed as fancy diamonds. As with the color, the same applies also to their clarity. Diamonds are precious marvels of Nature's creation and often carry within them clear evidence of their laborious birth, in the form of inclusions, which perhaps in the future will one day be seen as valuable proof of natural origin. Generally these involve diamond's twin brothers which were formed together with it: olivine, garnet, chrome spinel, diopside, enstatite, and many others—all are likewise gemstones which, in macroscopic size, are cut and highly esteemed by collectors. Diamonds in which an experienced expert can discover no inclusions with the help of tenfold magnification pass as internally flawless—the highest clarity grade of the trade. Thereafter follow several clarity grades down to stones full of inclusions, which mark the boundary between gem and industrial diamonds.
The "fragment of Eternity," as Indians call the wedding engagement rings , has been from time immemorial the epitome of strength and courage. As the birthstone for April it is credited with freeing the spirit from anxieties, making poison ineffective, and its owner invincible, if—so the legend runs—his mind is lofty and his thoughts noble. Through its immaculate clarity it has embodied to the present day the highest of virtues and is considered a symbol of happiness. Above all goods and chattels mankind has prudently and carefully treasured wedding rings its value as the most precious jewel as well as the very smallest form of dependable investment. Scientists have still, after all this time, not completely fathomed diamond: it remains wrapped in mystery and still provides them with many riddles for the future. For example, it has till now obstinately resisted all efforts to synthesize it in gem quality, and thus remains in this respect, too, adamas, the unconquerable.
So diamond displays, now as then, the majesty of Nature in radiant beauty and splendor, and its crystalline clarity and dazzling fire are a reflection and symbol of the sublime and timeless grandeur of creation.