Color analysis is really important for diamond and colored gems classification. Working technique is based on visual comparison and supported by electric tools for a careful diagnosis. Through the decades, a dedicated tool and a developing software improving its calculus ability based on day by day collected data were developed.
Diamond comparison set
Ten 0,50 ct Diamond comparison stones, with “Master” certification issued by the High Committee for Diamonds in Antwerp (HRD). In order to be considered Master, a diamond needs specific features, such as: excellent cutting, inclusions which are not over a few microns, no reaction if exposed to ultra – violet light and, most of all, its saturation must be in line with the lower color border. In light of all the just mentioned characteristic, the completion of the Diamond comparison set took many years.
Sarin DC3000 colorimeter
According to rules, the color evaluation must be performed on the basis of visual comparison. Nonetheless, a test performed through a colorimeter such as DC3000 makes the gemologist more confident. This tool, especially built for a gemological use, is really trustworthy: half error grade, either rife or failing. A wide spectrum light bundle crosses the examined diamond; the absorption values, gained through a spectrometer are developed through a complex software algorithm which gives back color grade on a D – Z scale.
The center of analysis Masterstone created, through the decades, an important tool for color reckoning. It is a UV – VIS NIR setup based on an integration sphere, an Ocean Optics high definition spectrometer and solarized optical fibers. This tool, result of a careful collaboration between gemologists and engineers, has two sources (one is halogen and the other high intensity stroboscopic xenon) ensuring a wide spectral extent ranging from 190 to 1100 mm. Evaluations can be performed in transmission or by reflection, through two different channels. The software, especially built, enhances the tool performances and makes it really irreplaceable.
Munsell color system is used as international standard to determine colors on the basis of three dimensional coordinates: shade, brightness and saturation. It is used in laboratory for color classification and consists of two gatherers with 48 multiple charts. Each of the charts contains 30 colors that can easily be put on top of the original.