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The round brilliant is the most popular diamond cut. Because of its popularity, assessment of this cut has been the subject of considerable research. This image shows a wide range of uses for this style in commercial jewelry, as well as loose polished diamonds and diamond crystals. The loose polished diamonds weigh 1.05-3.01 ct, and the rough crystals weigh 2.14-2.49 ct. Jewelry and loose polished diamonds courtesy of Ben Bridge Jewelers. Composite photo by Harold & Erica Van Pelt.
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GIA began its 15-year study of diamond cut by using a computer to model the way light behaves within a round brilliant cut diamond. From this model, GIA researchers developed proportion-based metrics to predict how diamonds would perform with regard to brilliance and fire. Continued research revealed several important variables that could not be ev...
Contexts in source publication
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... final brightness metric assumes a diffused, white hemisphere of light above the girdle plane of the diamond, with a dark circle located at the zenith of this hemisphere (see figure 10). The area below the girdle plane is dark. ...
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... and Craftsmanship. After speaking with dia- mond manufacturers and retailers, we verified a number of additional aspects of a diamond's physi- cal attributes as important: A diamond should not weigh more than its appearance warrants (i.e., dia- monds that contain "hidden" weight in their girdles or look significantly smaller when viewed face-up than their carat weights would indicate; figure 11); its proportions should not increase the risk of dam- age caused by its incorporation into jewelry and everyday wear (i.e., it should not have an extremely thin girdle); and it should demonstrate the care taken in its crafting, as shown by details of its finish (polish and symmetry). Diamonds that displayed lower qualities in these areas would receive a lower overall cut quality grade. ...
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... diamonds are described in the trade as "thick" or "heavy." A similar difference in value would apply if two diamonds had roughly the same diameter but one weighed significantly more (again, see figure 11). ...
Citations
... Optimizing proportions is a significant area of research in diamond cut, though it is not the subject of this paper. The interested reader will find an extensive literature for the standard round brilliant [7,11,12,18]. ...
We present an algorithm for enumerating all possible faceting arrangements of dihedrally symmetric diamond cuts. We first separate the question into enumerating crowns and pavilions. In each case, the method involves enumerating all plausible graphs within a fundamental domain, and then checking for planarity and triconnectivity using the Tutte spring embedding. Such graphs can be lifted to three dimensional convex crowns or pavilions via the Maxwell-Cremona correspondence.
... The value of rubies is also determined by how they are cut and polish. Diverse cuts produce different looks, which helps the ruby to have a more appealing visual presence [5]. Inclusions in a ruby is proportional to its clarity. ...
... Natural components present in rubies are called inclusions, and they are linked to geological phenomena including fissures, fractures, and voids [6]. Clarity is influenced by transparency, which is determined by opacity and is an indication of the ruby's capacity to transmit light [5]. Not only gemmology, but also manufacturing (cutting and drilling) [7], as well as the health and dentistry industries (laser technology) [8] will benefit from a comprehensive quantitative examination of rubies. ...
Several gemmology technologies, including loupes, microscopes, and dichroscopes, are currently utilised to assist gemstone traders in evaluating rubies. These tools, on the other hand, rely heavily on human vision for pictorial assessment. There are no standardized tools for determining ruby stone grading, other from those that rely on human vision, which can lead to errors. Gemmologists, stakeholders in the precious stone and manufacturing industries, as well as dental applications, would benefit from a standardized quantitative grading valuation of ruby stones. Extensive research is required to analyse the light characteristics of rubies. This paper presents a potential research overview of the Charge-Coupled Device (CCD) linear sensor to inspect the grading value of ruby stone based on its light characteristic. This research delves deeper into the relevant light properties of rubies for grading purposes. Numerous types of gemmological instruments are used for grading and appraising rubies, as well as their applications, are discussed in this paper. A standardized approach for quantitative grading valuation of ruby stones utilising a Charge-Coupled Device (CCD) linear sensor is offered due to the limits of current techniques and the strong demand for superior quality in the high-valued stone sectors.
... The gemology sector is tremendously profitable, but it is far more complex than many other industries, such as iron, silver, or gold, because the quality of the gems, particularly the high-demand gems such as ruby, diamond, and sapphire, do not depend solely on carat weight or purity. With many artistic, subjective, and cultural factors in grading techniques, the relevance is dependent on a much more complicated quality [6]. ...
Charge-Coupled Device (CCD) is a semiconductor chip with a light-sensitive sensor. The CCD has been used in many fields of engineering, including astronomy, medical sciences and processing. CCD is capable to detect light sources and convert this analogue signal into electrical signal. CCD is an integrated circuit that contains a large number of small photo elements with high sensitivity to light energy. The main focus of this research paper is on the review of CCD basic operating principle and construction, CCD characteristic, and the application of CCD in tomography system. The potential use of CCD in the gemological industry is also highlighted in this paper. Gemology is one of the important industries that considered profitable and crucial that deals with precious stones. This industry is in need of standardized grading valuation of gemstones as the current technique is prone to errors. An approach to the standardized grading technique is proposed where CCD tomography is used to detect and analyze the light distribution characteristic in ruby stones.KeywordsCharge-Coupled Device (CCD)GemologyLight distributionRubyTomography
... Many articles about various aspects of diamond grading have been published regarding color grading (King et al., 2006(King et al., , 2008, cutting decisions (Caspi, 1997), cut grading of round brilliants (Hemphill et al., 1998;Moses et al., 2004), symmetry (Geurts et al., 2011), crystal inclusions (Koivula, 2000;Kaminsky et al., 2000;Shirey and Shigley, 2013;Smith et al., 2016;Renfro et al., 2018), trends exclusively seen in large diamonds (Smith et al., 2017), and fluorescence (Moses et al., 1997;Luo and Breeding, 2013;Bouman et al., 2018;Breeding and Eaton-Magaña, 2019). Recounting the specifics of the grading process or the mechanics of fluorescence observations is beyond the scope of this article. ...
Colorless to light yellow or brown diamonds with a “D-to-Z” color grade make up the overwhelming majority of the world’s gem diamond trade. Besides clarity features (such as inclusions) and fluorescence observations, however, comparatively little has been explored and published regarding the distinguishing characteristics of these diamonds. The vast majority are type Ia, with infrared spectra showing very high concentrations of nitrogen aggregates. This population of diamonds could not have been subjected to HPHT decolorizing treatment or been laboratory grown, and thus they have been spectroscopically scrutinized in much less detail than the far more rare natural diamonds of types IIa, IIb, and IaB, which need to be investigated as potentially color-treated or synthetic.
This study examines a large sample set comprising the full complement of D-to-Z diamonds submitted to GIA laboratories during a significant portion of 2017. The data were evaluated on the basis of diamond type properties, as well as distribution among various grading quality factors, to provide an unprecedented glimpse into the role of these diamond types and differences in their geologic conditions of formation.
... The comparison between the two verified the feasibility of studying lightness through diamond models. What's more, Moses et al (2004) believed that the quality evaluation of diamonds should not only unify the observation environment, consider personal preferences and understand the market tendency, but also comprehensively take the interaction of various facet of diamonds integrated into account instead of being limited to a few attributes. Reinitz et al (2001) emphasized that every facet matters in a round brilliant diamond. ...
The quality of a diamond is not only affected by the 4Cs but also affected by fire and scintillation. The relationship between the color, clarity, fluorescence, and scintillation of a diamond is obtained by associating its scintillation area and gemological characteristics. Take images of 18 round bright cut diamonds in total, for each to rotate 30° to take one and get 12 images by rotating a circle. Rotate the images to the same angle, cut out the square image of 1000*1000 pixels, then calculate the color difference of the image of adjacent angles, and then judge whether scintillation occurs at each point to get the scintillation area of the diamond. The results showed that the lighter the color, the better the clarity and the weaker the fluorescence, then the larger the scintillation area and the more obvious the scintillation. This indicates that the scintillation area has a certain reference value for diamond quality evaluation.
... The classification results by naked eyes are compared with the results by color difference. Hemphill et al. (1998) presented the weighted light return (WLR) to study the interaction of light with a fully round-brilliant-cut diamond; Reinitz et al. (2001) analyzed the interaction of light with fully faceted colorless symmetrical round brilliant cut diamonds of various proportions and dispersed colored light return (DCLR, the metric for fire) and WLR (the metric for brilliance); Thomas et al. (2004) asked diamond manufacturers, dealers, retailers, and potential consumers to evaluate diamonds' brightness, fire; Gilbertson (2013) studied the patterns of light and dark, using computer-generated color-coded contrast maps in facet planning can improve apparent brightness, optimizing a gemstone's appearance; studied brightness, fire, sparkle and scintillation of round brilliant diamonds and their modern crystals strontium; Liu et al. (2016) calculated the color difference of the same pixel point in two images to evaluate scintillation of the diamonds; Jose et al. (2007) discussed several illumination effects in round brilliant gemstones and present maps to evaluate their brilliance, fire, and scintillation. ...
The synthetic moissanites' changes (silicon carbide, SiC) of fire and brightness is evaluated quantitatively by color difference and the result is verified by naked eyes. Each sample under the LED white lighting is taken 6 images by 0 ° to 150 ° rotation at 30 ° intervals. Program to calculate color difference and analyze the color difference of adjacent rotation angle. As for every sample, get 5 group data sheets, every group has 3000 × 3000 color difference. According to the data, all samples are divided into three grades, Fine (F), Good (G), Excellent (EX). The synthetic moissanites' changes quality of fire and brightness is evaluated by analytical method, principal component analysis and entropy method and by 4 professional and 5 non-professional gem researchers' eyes. There is a 100% similarity by comparing the classification results used the entropy method and by naked eye. Color difference can be used to evaluate the changes quality of fire and brightness. Because synthetic moissanites' body color influence non-professional gem researchers' results easily, the evaluated synthetic moissanites' color grade should be above J color.
... The classification results by naked eyes are compared with the results by color difference. Hemphill et al. (1998) presented the weighted light return (WLR) to study the interaction of light with a fully round-brilliant-cut diamond; Reinitz et al. (2001) analyzed the interaction of light with fully faceted colorless symmetrical round brilliant cut diamonds of various proportions and dispersed colored light return (DCLR, the metric for fire) and WLR (the metric for brilliance); Thomas et al. (2004) asked diamond manufacturers, dealers, retailers, and potential consumers to evaluate diamonds' brightness, fire; Gilbertson (2013) studied the patterns of light and dark, using computer-generated color-coded contrast maps in facet planning can improve apparent brightness, optimizing a gemstone's appearance; studied brightness, fire, sparkle and scintillation of round brilliant diamonds and their modern crystals strontium; Liu et al. (2016) calculated the color difference of the same pixel point in two images to evaluate scintillation of the diamonds; Jose et al. (2007) discussed several illumination effects in round brilliant gemstones and present maps to evaluate their brilliance, fire, and scintillation. ...
The synthetic moissanites' changes (silicon carbide, SiC) of fire and brightness is evaluated quantitatively by color difference and the result is verified by naked eyes. Each sample under the LED white lighting is taken 6 images by 0 ° to 150 ° rotation at 30 ° intervals. Program to calculate color difference and analyze the color difference of adjacent rotation angle. As for every sample, get 5 group data sheets, every group has 3000 × 3000 color difference. According to the data, all samples are divided into three grades, Fine (F), Good (G), Excellent (EX). The synthetic moissanites' changes quality of fire and brightness is evaluated by analytical method, principal component analysis and entropy method and by 4 professional and 5 non-professional gem researchers' eyes. There is a 100% similarity by comparing the classification results used the entropy method and by naked eye. Color difference can be used to evaluate the changes quality of fire and brightness. Because synthetic moissanites' body color influence non-professional gem researchers' results easily, the evaluated synthetic moissanites' color grade should be above J color.
... These three features, i.e., D1, D2, and FacetAngle, are obtained from the company supporting this project. They select the features partly based on the standard diamond evaluation (Gemological Institute of America; see [5] for more details) and experimental correlation with the offline manual measurement. To achieve the inspection task, we resort to a visual inspection algorithm that verifies these criteria from an image. ...
In this paper, we present an automated system for the visual inspection of cubic zirconia (CZ) cut quality. In particular, we inspect the cut quality from pavilion facets of the CZ. For the hardware, the system includes a computerized-control mechanical part that performs both the task of feeding the CZ to the inspection station and the task of separating the gemstone according to the inspection result. In terms of software, we propose an image processing algorithm that consists of two major steps. For the first step, pavilion facets are extracted from the CZ image acquired from the pavilion side. In particular, we resort to the idea of 1-D edge detection in conjunction with random sample consensus line fitting for the pavilion facet extraction. For the second step, a set of measures derived from the extracted facet structure are calculated and are used for cut quality judgment as either accept or reject. The metrological analysis of the system is also investigated. We perform an experiment to inspect 1756 object images consisting of both good and bad samples. The performance of our system yields to about 5.21% of false reject rate and 0% of false acceptance rate. The system can inspect CZ with a rate of 1 sample/s.
... 93). With the goniometer, we focused on measuring the bezel facets and pavilion facets since the angles between these facets and the table have the most significant impact on the cut grade (Hemphill et al., 1998;Reinitz et al., 2001;Moses et al., 2004). We also measured the star facets on one of the round brilliants (no. ...
A classic two-circle reflecting goniometer was used to measure inter-facet angles on five faceted diamonds that included round brilliants and fancy shapes. The instrument provided significantly better precision (to within 2 minutes, or 0.034 degrees) than the non-contact optical scanner that is customarily used at GIA for this purpose. With some procedural modifications, the goniometer could make measurements of all inter-facet angles, including the pavilion facets. The technique is potentially valuable for producing a well characterized set of reference stones for calibrating non-contact optical scanners.
... We therefore became concerned that the coatings on the earlier samples used in this testing Visual Observation Testing. We conducted two rounds of visual observation tests to compare the face-up appearance of the Diamantine product with that of colorless round-brilliant CZs and diamonds based on GIA's cut-grade parameters (Moses et al., 2004). Our goal was to see if the coating improved the appearance of these CZ samples, producing a stronger resemblance to diamond. ...
Over the past several years, diamond simulants have entered the market that consisted of colorless cubic zirconia reportedly coated with a thin layer (e.g., represented to be 30-50 nm) of nanocrystalline diamond particles embedded in a matrix. One manufacturer, Serenity Technologies (Temecula, California), has marketed this material as Diamantine. SIMS chemical analysis of samples obtained from Serenity in October 2009 indicated a very thin (∼5 nm) film of carbon (along with Al and Ti) on the CZ surface. Durability tests performed in conjunction with SEM imaging demonstrated that the thin coating does not completely withstand typical gemstone cleaning and handling procedures. The only standard gemological technique that could establish the presence of a coating was EDXRF spectroscopy, which detected Ti from the adhesion layer deposited on the CZ during the initial part of the coating process.
