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How to determine the value of a diamond

According to reports by the Gemological Institute of America (GIA), recently in the laboratory, located in carlsbad (Carlsbad), learned a new jewelry material, manufactured by Kyocera, which is characterized by intensively manifested opalovidnogo. In manufacturing such a material can act as an imitation of opal or "opalovidnogo material" (the"opal-like product").

Gemological research conducted with the use of a standard set of methods allowed to determine the material as the material (natural or synthetic), that mimics the properties of natural opal.

Table 1. Comparative characteristics of the new jewelry material and opal.

 New materialOpal
Specific gravity, g/cm3 1,35 2,00
The refractive index 1,49 1,37-1,47

In determining the nature of luminescence in ultraviolet rays, the samples of the investigated material showed the following features:

samples with basic white color had a glow in shades of blue, with a weak intensity in the short wavelength range of UV lighting and with medium intensity in the long wavelength range;

samples with black the main color was glow in orange tones with a weak intensity in the short wavelength range of UV light and was inert to long-wave range.

Subsequent in-depth study of this material showed that it includes a significant amount of organic polymeric materials and silica. The organic polymer material is different from the conventional polymer impregnation of synthetic opals.

Microscopic examination revealed the following features of the structure of this material: the distribution pattern of the color was not like the characteristic of most synthetic opals (had a random distribution pattern in the absence of optical effects "snakeskin" and "network of polygonal cells" (Fig.1).

Fig.1 Microscopic structure a new imitation opal

 

 The article notes that this new material visually is a very good imitation of natural opal, but is diagnosed easily when learning standard Gemological methods.

 

Authors:

  • Nathan Renfro – the identification of gemstones and microscopic studies of inclusions;
  • James Sigle – leading researcher at the GIA in carlsbad, California.

 Source: GEMS&GEMOLOGY Spring 2018, p.60-62.

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