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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.
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 ...
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Polyhedral representation of spinel MgAl 2 O 4. Spinel (/ s p ɪ ˈ n ɛ l, ˈ s p ɪ n əl / [7]) is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula MgAl 2 O 4 in the cubic crystal system. Its name comes from the Latin word spinella, a diminutive form of spine, in reference to its pointed crystals. [5]
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.
Lab-grown diamonds of various colors grown by the high-pressure-and-temperature technique. A synthetic diamond or laboratory-grown diamond (LGD), also called a lab-grown diamond, [1] laboratory-created, man-made, artisan-created, artificial, synthetic, or cultured diamond, is a diamond that is produced in a controlled technological process (in contrast to naturally formed diamond, which is ...
Since the per carat price of diamond shifts around key milestones (such as 1.00 carat (200 mg)), many one-carat diamonds are the result of compromising cut for carat. Some jewelry experts advise consumers to buy a 0.99-carat (198 mg) diamond for its better price or buy a 1.10-carat (220 mg) diamond for its better cut, avoiding a 1.00-carat (200 ...
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]