4C分级对小克拉彩色黄钻价格的影响分析

近十年来,彩色钻石市场日益火热,其价格亦逐渐增长,但限于数量稀少等原因,彩色钻石市场未能像无色钻石一样建立起成熟的报价表制度。目前国内外对其价格方面的研究并不多,因此对彩色钻石价格影响因素的研究显得尤为重要。本文基于某中大型钻石批发公司提供的切工为垫型的1 031颗彩色黄钻的全球报价数据,重点对0.20~0.91ct的小克拉彩色黄钻价格的影响因素进行了分析。结果显示,4C分级(克拉、净度、切工、颜色)和彩色黄钻的价格存在不同程度的线性关系,重量(克拉)通常和价格呈正相关关系;颜色对彩色黄钻报价影响较大,切工对彩色黄钻报价影响较小。最后,量化小克拉彩色黄钻4C等级差对其报价影响发现,净度、颜色、切工存在不同大小的等级差溢价;不同净度、颜色、切工对彩色黄钻的价格增长倍率等亦存在不同程度的影响。     

钻石颜色分级的定量探讨

钻石的颜色是钻石质量评价4C（颜色color,净度clarity,切工cut,重量carat）的重要标准之一。目前钻石的颜色分级仍然依靠经验丰富的专业人士,利用人眼对颜色的分辨率或市场上钻石分级比色石来进行。但此种方法带有主观性。为了将钻石颜色分级工作变得客观、准确,应用色度学CIE1931系统,主要通过海洋公司生产的USB4000光纤光谱仪对I—MN色级共55颗钻石进行测试,将宝石颜色量化来探讨钻石颜色测试的可行性。实验表明,运用色度学原理,不同色级钻石的参数具有一定的规律,建立将钻石颜色量化的体系,将不同色级钻石的颜色进行量化,并运用到实际分级工作中具有一定的可行性。     

GIA宣布实施钻石切工分级体系

GIA宣布，将从2006年1月1日起开具新的钻石分级报告。对GIA的D-Z色级、FL-1。净度级的圆形明亮琢型钻石，在新的报告中除了颜色、净度和克拉质量分级信息外，还包括切工分级信息。GIA安排，从8月1日～12月31日使钻石业界熟悉这个新的钻石切工分级体系，了解其优点。     

钻石分级的实际应用

钻石的质量评价有4个方面:颜色、净度、切工和重量。其中颜色、净度与切工的分级都有严格的标准,须有专门知识、经验与设备。但在不具备这些条件时,若能掌握钻石分级要点,也能对钻石质量作出有益的评估,为选购钻石提供参考。1 钻石的色级评估 钻石有多种颜色,色级的评定,仅对无色至浅黄色(褐)的钻石而言。一颗钻石,属于那一色级,要通过与标作对比确定,表1是钻石色级的划分。在没有标样时,高色级的钻石(96至100色),即使是训练有素的专业人     

标准光源对红宝石颜色影响的研究

红宝石的颜色质量一直是影响其市场价值的重要因素之一。近些年来，我国的宝石研究者已经开始着手做红宝石颜色分级和评价工作．并试图将分级结果与价格进行紧密联系。就目前为止，国际上仍没有对红宝石颜色分级体系的建立达到统一共识，尤其对于红宝石在不同用途上灯光的选取存在较大差异。     

从消费者角度看钻石的4C分级和新的国家标准

钻石是唯一可以用4C标准估价的宝石. 从消费者角度, 对钻石4C的追求有主次之分, 依次为质量、颜色、切工、净度. 新的钻石分级国家标准较原国家标准更趋完善, 但仍有一些有待补充之处.     

国际拍卖市场彩色钻石价格(值)影响因素统计分析及其启示

近年来彩色钻石(简称彩钻)在国际拍卖市场上的重要性越来越明显,统计、梳理和定量分析近十年来苏富比、佳士得两大国际著名拍卖公司的彩钻拍卖记录,对研究彩钻价值的影响因素及其分级、价值评估具有十分重要的意义。研究结果显示,彩钻价格主要建立在颜色稀有程度及消费者偏爱之上,对价格影响最大的是其颜色色系、色彩瑰丽程度(饱和度、亮度和次要色调);克拉单价通常与大小呈正比;净度、拍卖时间、来源(品牌)、类型等对其成交价格也有一定的影响。合成和经优化处理的彩钻可能会影响部分彩钻的价格,但总体上,其价格和天然彩钻价格之间没有发现必然联系。另外,高档彩钻在金融危机期间的表现显示其商品属性已从一般的奢侈消费品转变为资产投资品。上述结果说明,色彩、饱和度、亮度和次要色调是影响彩钻品质最重要的因素,就此而言,我国可参考美国GIA彩钻分级体系和澳大利亚力拓集团粉红色钻石的分级体系来建立适合中国市场的彩钻分级标准。     

镶嵌钻石4C分级的概念与技术

镶嵌钻石的品质分级可采用与裸钻相似但又有所不同的概念与技术，颜色分级可采用宝石显微镜配合的比色石支架的方法，将度分级可采用白背景技术涌除映像的影响，对切工可采用目估评价的方法。对比性实验研究表明，应用上述技术方法，可使镶嵌钻石的品质分级达到相当高的可信度。     

透射法在山东蓝宝石颜色量化中的应用（下）

山东蓝宝石在反射光下近黑色,无法适应国际上较通用的有色宝石品质分级体系。文章根据该产地蓝宝石的颜色特征,通过对比实验探讨最佳颜色测试方法,为山东蓝宝石颜色分级体系的建立提供理论支持。研究表明：透射法测试能更好地表征与区分蓝宝石的颜色。本实验根据色度学原理,以CIE1976Lab均匀色空间为载体,对透射条件下山东蓝宝石的颜色参数（明度、色调、饱和度）进行量化分析,为山东蓝宝石颜色分级体系的建立提供参考。     

透射法在山东蓝宝石颜色量化中的应用（上）

山东蓝宝石在反射光下近黑色,无法适应国际上较通用的有色宝石品质分级体系。文章根据该产地蓝宝石的颜色特征,通过对比实验探讨最佳颜色测试方法,为山东蓝宝石颜色分级体系的建立提供理论支持。研究表明：透射法测试能更好地表征与区分蓝宝石的颜色。本实验根据色度学原理,以CIE1976Lab均匀色空间为载体,对透射条件下山东蓝宝石的颜色参数（明度、色调、饱和度）进行量化分析,为山东蓝宝石颜色分级体系的建立提供参考。     

GemDialogue和GemSet颜色系统在有色宝石颜色描述和分级中的应用

国际贸易中有色宝石的报价主要是按其总品质级别和克拉质量给出的.目前,国际上较为广泛采用的有色宝石的分级体系主要有美国宝石学院和美国宝石协会的两个体系.在有色宝石总品质中起决定作用的是颜色,对宝石颜色的描述和分级分别采用的是GIA的GemSet和Howard Rubin的GemDialogue颜色系统.主要介绍这两个系统的特点以及它们在有色宝石颜色描述和分级中的应用方法及应注意的问题.     

首饰蜡镶铸造中宝石失色问题的探讨

蜡镶铸造是一个复杂的工艺过程,影响产品质量的因素众多,尤其是宝石要承受高温焙烧和浇铸时高温金属液的热冲击.任何一个因素都可能使宝石出现碎裂或外观改变.对蜡镶铸造过程中经常出现的宝石失色问题进行了原因分析,并提出了相应的解决措施.     

蓝色蓝宝石的颜色分级初探

在彩色宝石的质量分级中, 颜色是最重要的评价标准. 运用Photoshop图形处理软件, 对世界著名产地的蓝色蓝宝石进行颜色测试, 确定其H, S, B值, 进行了颜色分级. 讨论了影响颜色分级的因素及存在的问题, 提出了解决方案.     

Modelling the consensus and differences between assessors inspecting the colour quality of apples by ‘tree‐based modelling’

This research investigated the consensus and differences between different quality inspectors assessing the colour quality classification of a two‐coloured apple variety (Malus domestica Borkh cultivar ‘Jonagold’). An image analysis system measured the colour characteristics objectively. These objective measures formed the basic reference to compare the grading behaviour. Different quality inspectors were asked to assess the colour quality of different sets of apples applying the commercial quality standards. Agreement and association measures of the intra‐inspector contingency tables indicated a moderate ability of the inspectors to reconstruct their own quality classification. If the intra‐agreement and intra‐association were lower than a threshold, the repeatability of the inspector's assessments was considered as too poor and his classification results were omitted from the model development that simulated the apple colour classification behaviour. The statistical method ‘tree‐based modelling’ was applied to connect the individual quality assignments with the objective apple colour measurements. These models indicated that the blush colour was more important than the blush area for the quality assessment.The individual grading decision models were compared by correspondence analysis. Four different grading archetypes were detected and simulated. The predictive power of the four archetypal models was much higher than the predictive power of a consensus model including all inspectors. These results underlined the fact that poorly defined commercial standards lead to different quality interpretation. © 2000 Society of Chemical Industry     

Colouring our foods in the last and next millennium

Summary Colour in one form or another, has been added to our foods for centuries. It is known that the Egyptians coloured candy, and wine was coloured as long ago as 400  bc . The developing food industry had available a vast array of synthetic colours in the late 1800s. This led to colours being added for decorative purposes and unfortunately to disguise low quality foods. There was no control over this use of colour and so inevitably legislation came into force. In particular this was as a result of health concerns over some of the toxic compounds used. An established list of permitted synthetic colours eventually came into force in most countries early in this century. In the last twenty years however, consumers have become increasingly aware of the ingredients in their foods and as such they require foods to be as 'natural' as possible. This combined with technological developments has fuelled the increase in the usage of naturally derived colours. Today the food industry has an extensive colour palette available, allowing selection of the most suitable colour for their application requirements. Legislation is also in place to protect the consumer. Colour suppliers are however constantly striving to improve the technical and physical properties of their colour portfolio, to make the use of colour easier, to improve the stability and to meet customer demands on the functional additives used within colour formulations. This paper will review all colours in terms of recent developments and regulations as well as addressing the question of the future of colours in the next millennium.     

Red wine quality: Correlations between colour,aroma and flavour and pigment and other parameters of young Beaujolais

In 15 young Beaujolais red wines from the 1974 and 1975 vintages statistically significant linear correlations were found between overall quality and the contents of total pigments, total anthocyanins, coloured anthocyanins and tasters' mean colour scores; and also between flavour and the contents of total pigments and total anthocyanins. In 1974 additional significant correlations were found between (a) overall quality and wine colour density; non-coloured anthocyanins and pH, (b) flavour and colour scores and coloured anthocyanins, (c) aroma and total pigments, total anthocyanins, coloured and non-coloured anthocyanins and pH and (d) the chemical parameters of pH and total pigments and total anthocyanins. In 1975 flavour was correlated also with non-coloured anthocyanins and pH. The results demonstrate the desirable effects of anthocyanins on wine flavour and quality, whereas the polymeric pigments formed on ageing of Beaujolais appear to be indifferent features of quality. Thus, the negative correlations found between quality factors and wine ?chemical age’? tend to support the opinion that most Beaujolais should be drunk young. Comparison of the results with data on Australian and Swiss red wines suggests that sulphur dioxide affects not only quality itself but also the nature of the quality correlation found. Simple colour measurement of acidified wine provides a useful indication of quality in young red wines of the same grape cultivar and age, having minimal sulphur dioxide content.     

电子清纱与纱疵分级的最新发展

介绍了国外最近推出的能清除有色异纤电子清纱器以及国内这一领域研究所取得的最新成果－－能清除外来有色及无色的异纤电子清纱器；提出了应根据清纱工艺，针织需要及细节弱环断头进行“全纱疵分级”的概念。     

精纺羊绒匹染产品染整工艺的探讨

精纺羊绒产品特别是深色产品匹染时极易出现色花,边中色差等染色疵点,针对这一问题,我们对染色工艺曲线,助剂用量,后整理工艺等进行了探讨,并找到了比较适合精纺羊绒产品的染色及后整理工艺,大大提高了产品质量。