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The first crystalline artificial diamond simulants were synthetic white sapphire (Al 2 O 3, pure corundum) and spinel (MgO·Al 2 O 3, pure magnesium aluminium oxide). Both have been synthesized in large quantities since the first decade of the 20th century via the Verneuil or flame-fusion process, although spinel was not in wide use until the ...
In 1838, in the inventory of crown items, the stone under the cross was called a “large ruby”, and in the inventory of 1865 it was already listed as “an irregularly shaped spinel ruby, worth 100,000 rubles”. [15] Since 1967, the crown, and along with it the historical spinel, has been an exhibit of the Diamond Fund.
One of Verneuil's sources of inspiration for developing his own method was the appearance of synthetic rubies sold by an unknown Genevan merchant in 1880. These "Geneva rubies" were dismissed as artificial at the time, but are now believed to be the first rubies produced by flame fusion, predating Verneuil's work on the process by 20 years.
Detailed view of the recreated great Golden Fleece of king Louis XV of France. Below the 107 carats (21.4 g) spinel Côte de Bretagne hangs the French Blue diamond and the fleece itself, set with hundreds of yellow diamond replicas. The Tavernier Blue was the precursor diamond to the Blue Diamond of the French Crown (aka the French Blue).
The mineral spinel MgAl 2 O 4 has a normal spinel structure. In a normal spinel structure, the ions are in the following positions, where i, j, and k are arbitrary integers and δ, ε, and ζ are small real numbers (note that the unit cell can be chosen differently, giving different coordinates): [16]
The curvature observed in this synthetic color-change sapphire is due to a process known as the Verneuil process or, flame fusion. During the Verneuil process for synthesizing gems, a fine crushed material is heated at extremely high temperatures. The powdered gem mineral is then melted (or a metallic mixture directly burned in an oxygen flame ...
The fates of Ohio State and Miami were the two major unknowns entering the College Football Playoff rankings that revealed the future of the field.
The spinel products business is being pursued by two key U.S. manufacturers: "Technology Assessment and Transfer" and the "Surmet Corporation". An extensive NRL review of the literature has indicated clearly that attempts to make high-quality spinel have failed to date because the densification dynamics of spinel are poorly understood.