Cushion-cut green lab-grown diamonds do exist in the market, and they usually have high clarity and natural color. Not only are these diamonds sought after at auctions, but their unique color and cut also make them a popular choice for jewelry collectors and investors.
What are the color grading standards for cushion-cut green lab-grown diamonds?
The color grading standards for cushion-cut green lab-grown diamonds mainly refer to the GB/T 16554-2010 Diamond Grading standard. This standard specifies the grading rules for the color, clarity and cut of natural unmounted and mounted polished diamonds.
Color grading uses the colorimetric method, using colorimetric stones, colorimetric lights, colorimetric plates or colorimetric papers to evaluate the color grade of diamonds.
Although the GB/T 16554-2010 standard is mainly applicable to diamonds in the colorless to light yellow (brown, gray) series, diamonds in the non-colorless to light yellow (brown, gray) series can also refer to this standard for color grading.
This means that the color grading of green diamonds can be evaluated with reference to the color grade comparison table in this standard.
The De Beers Diamond Research Institute grading standards also provide detailed information on color grading, including methods for color assessment using contrast colors. These contrast colors are compiled according to standards recognized by leading international grading laboratories, including cross-color contrast colors and color contrast colors at different grades.
How to identify the authenticity of cushion-cut green laboratory-grown diamonds?
Identifying the authenticity of cushion-cut green laboratory-grown diamonds requires a combination of gemological and spectroscopic techniques. The following are detailed identification methods:
UV-Vis, IR, and Raman spectroscopy: These spectroscopic techniques can detect the chemical and physical properties of diamonds. For example, UV-Vis and IR spectroscopy can observe absorption peaks at specific wavelengths, which can help distinguish natural diamonds from laboratory-grown diamonds.
Photoluminescence spectroscopy: Using laser spectroscopy (PL) imaging technology, defect concentrations at different growth stages can be observed. For example, the fluorescence microscope (DiamondView) developed by DeBeers can be used to distinguish high-grade silicon carbide (HPHT) grown diamonds from natural diamonds.
Thermal conductivity: The thermal conductivity of lab-grown diamonds is usually higher than that of natural diamonds, and the thermal conductivity can be measured to assist in identification.
Internal and external features: Microscopic examination is an important tool in standard gemological research. By magnifying and observing the sample, anomalous double refraction patterns related to crystal growth can be found, which may reveal the growth or post-processing process of the diamond.
Refractive index: By measuring the refractive index of the diamond, it can be further confirmed whether it is a lab-grown diamond.
Professional laboratory identification: Send the diamond to a professional laboratory for identification, such as IGI International Gemological Institute, HRD Antwerp and the Gemological Institute of America (GIA). These laboratories will issue detailed identification reports and perform laser inscription on the diamond waist to ensure consumers' right to know.
Color center and defects: The impact of defects such as color center on the color of the diamond is also an important basis for identification. Different types of defects will absorb specific wavelengths of light in the ultraviolet to visible and infrared ranges, and these defects can be detected by absorption spectroscopy.
What are the physical and chemical differences between cushion-cut green lab-grown diamonds and natural green diamonds?
Cushion-cut green lab diamonds are virtually indistinguishable from natural green diamonds in terms of physical and chemical properties. Lab-grown diamonds are made by synthesizing carbon under high pressure and temperature to simulate the Earth's natural processes, or by stacking layers of it in a chemical vapor deposition (CVD) process using hydrocarbon gases
Lab-grown diamonds and natural diamonds are almost identical in chemical composition, physical properties, and optical properties. From a physical and chemical point of view, cushion-cut green lab-grown diamonds are indistinguishable from natural green diamonds. These aspects are almost identical, but there are still subtle differences that can be detected with professional equipment. For example, the growth environment and conditions of lab-grown diamonds are different from those of natural diamonds, which can cause minor differences in their internal structure or crystal arrangement. Although these differences are not obvious, they are detectable by professional gemologists with special equipment. Lab-grown diamonds are generally less expensive than natural diamonds and there is no risk of "conflict" diamonds. Lab-grown diamonds are created in a controlled environment by simulating natural processes, starting with a carbon seed, which is treated with extreme heat and pressure, and then cut and polished like natural diamonds
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