ImaGem Inc. is an information company that uses automated technology for grading and identifying gems. Its parent company, ImageStatistics, provides imaging and image processing applications for the medical, pharmaceutical, manufacturing, and chemical sectors. The company was established following research into human perception and the development of ImageStatistics, a statistical tool by Lalit K. Aggarwal. The company's systems use optics and imaging software to automate diamond grading. ImaGem also analyzes Light behavior information based on precise and repeatable measures; three complementary dimensions of brilliance, intensity and sparkle. ImaGem has created a system of uniquely identifying and registering (fingerprinting) a stone without any need for laser inscription. By offering all this information, ImaGem has promoted decision-making and efficiency in the gem industry supply chain. In 1998, ImaGem Inc. was incorporated in the state of Pennsylvania, USA after funding from a major retailer, Ben Franklin Technology Partnership, and private funding. The company has developed an integrated technology to collect image data for diamonds and gemstones, analyze it using direct measurement methodology and grade for precise and repeatable measurements.
Breakthroughs and technological advances
Color Color grading of diamonds (see Diamond color) and gemstones is subjective - an individual compares a subject stone under a light source to a master stone and assigns a color grade. This approach is well-known to provide a color grade that is not repeatable because, in the past, there has been confusion among different methods of grading used in various labs. Because of this, ImaGem solved several problems which contribute to a lack of precision and repeatability in color grading.
The human perceptual system is not capable of precise color memory. Perception of color by an individual can vary during different times of the day, by environmental factors, and by eye color. Light sources are not standardized either for their color temperature or their UV component. Master Stones used in grading are generally of a particular weight at a grading lab. Different labs may use master stones of different weights. All these factors therefore, in varying degrees, contribute to inconsistent color grading as it has been practiced in previous years. ImaGem’s color grading system was designed based on measurements with a system error of 1/400 of 1% to achieve high levels of precision and repeatability. The system assigns grades within 1/3 of the color grading system used by major diamond grading labs. The color grading system corrects for weight and fluorescence and uses CIE Chromaticity System (see CIE 1931 color space).
Fluorescence The most frequent color of fluorescence in diamonds is blue, but it occurs in many other colors. Fluorescence may be exhibited at both short-wave and long-wave UV. The strength of fluorescence also varies from slight to high. The value of a diamond may be affected by the presence and strength of fluorescence in a diamond. As a matter of personal taste, some people prefer a diamond with fluorescence. Although some may disagree, it is generally thought that fluorescence may influence perception of body color in a diamond and hence, its color grade. Standard fluorescence grading is done by a trained gemologist using master stones and assigning a grade after projecting short and long-wave UV. Since a standardized lighting source has not yet been defined, and because of the subjective nature of the process, fluorescence grades in the past have not been repeatable. Although instruments for measuring fluorescence have existed for some time, the process for measuring low-levels of fluorescence takes time and therefore may not be practical for fluorescence grading of diamonds. There are primarily three problems that need resolution to measure fluorescence accurately and repeat ably.
The measurement of fluorescence in diamonds must be done quickly. To achieve accuracy and repeatability, it must use light sources that are highly reliable, both in terms of their spectra characteristics and emission level. ImaGem developed a proprietary system to measure fluorescence in a diamond in a fraction of a second. To achieve accuracy and repeatability, light sources are standardized and multiple readings are taken around a diamond and then averaged. This technique is used to measure fluorescence in polished as well as rough diamonds, and can also be used for other gemstones. The measurement should not depend on the size of a stone.
Clarity In diamonds and gemstones there is a need to identify that a product sold is what it is claimed to be. Also, one needs to determine if a gemstone has been treated or filled, or manufactured using composites. In rough gemstones, presence of foreign matter and inclusions affects the value of the rough material and is considered in planning how the stone will be cut to manufacture polished gemstones. Features in rough as well as finished goods are also used to fingerprint a gemstone. Finally, once polished goods are manufactured they require an assessment of their quality based on presence or absence of inclusions. Any activity related to the above, in general, deals with clarity of a gemstone. ImaGem developed patented technology to precisely map, and measure inclusions in gemstones. There were several technical challenges ImaGem had to overcome in order to map inclusions:
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