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Identification of imitation black diamond

During one of the diagnostic examinations in our laboratory, the study of jewelry inserts in jewelry imitating black diamond, identified a variety of boron carbide a black color.

Microscopic examination it was observed that the insert is opaque, including the chips, and structural-textural features of the inserts resemble the ceramic material is a massive structure, many small surfaces, giving a glare.

The use of the tester "Presidium Gem Tester" showed the value of thermal conductivity similar to diamond. Measurement of specific gravity and refractive index was not available as a result of the fact the stone setting in the product.

Attempts to remove the spectrum of Raman scattering from the crown is not successful. To results have been with small area of chipping at the girdle. The main peak of the spectrum with the exciting laser radiation with the wavelength of 532 nm. corresponded to the value 1090 Rel. cm-1, which corresponds neither to the diamond or moissanite. When searching for similar spectra of the biggest match was the material known as tetracarbon forest.

Tetracarbon boron is a relatively rare imitation of a black diamond used in the manufacture of jewelry in the Russian Federation. For the first time the use of this material (or similar) as the jewelry insertion was established the Indian gemologists from "Gem Testing Laboratory" (India, Jaipur), and an article was published in "Gems and gemology. 2013 Fall. Pp 180-181.".

Now it is established that boron carbide has found its application in jewelry and in Russia.

Table 1. Comparative table of main physical-chemical characteristics of tetrabromide boron and diamond.

Tetracarbon BoraDiamond
Chemical formula B4C (B12C3) С
System Trigonal Cubic
Specific gravity, g/cm3 2,52 3,47-3,55
Microhardness, GPa 49,1 93,1-98,6
The refractive index 3,231 2,417
Thermal conductivity, W/(m*K) 121,4 1001-1600

When analyzing the material the jewelry insertion was used Raman-luminescent spectrometer EnSpectr R532.

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