版上姐妹们选石头的时侯都在纠结HCA指数。 我在刚入Tiffany， training 的时候没有提及任何相关的东西， 问了不少同事大家也都没有听说过。 今天终于有幸联系到了总部的一位 珠宝鉴定负责人， 请教关于HCA的问题。 同时我也去了大家用的这个网站研究了一下 ，[url=http://www.pricescope.com/tools/hca]http://www.pricescope.com/tools/hca[/url]， 这个网站标出 需要用一下的report ：AGS and 2006 GIA and IGI reports。但Tiffany是有自己的lab的，有着更严谨的标准， 所以导致世界上只有0.02%的钻石才能命名为tiffany diamond。 为了给大家更专业的回答，我把珠宝鉴定负责人的邮件copy在下边，这样大家就可以更好的了解了。

The HCA is a very simplistic way to judge a diamond. It is based on the Tolkowsky proportions from the 1920’s. The formula only asks for a few proportion inputs and calculates based on slight deviations from an exact set of proportion metrics. This is very antiquated, as we now know, many other factors contribute to the visual of a diamond and every individual will have their preferences. Polish, facet and proportional symmetry, varying combinations of girdle thickness, percentages, angles, culet sizes, star lengths/pavilion half lengths and so forth… help to determine the varying degrees of Brilliance, Dispersion and scintillation. Tiffany has fortunately calculated all of these factors and will only sell diamonds that fall within a prescribed set of parameters that we feel represents the full spectrum of exquisite visual beauty. We do not sell any poorly crafted diamonds and allow our customers the freedom to choose what they prefer in a diamonds light performance, without sacrificing the inherent integrity of a diamonds physical attributes.

When a customer is set on utilizing simple means to ascertain a numerical value that supposedly represents the visual characteristics of a particular diamond, they unfortunately, lose out on making an informed decision based on their personal preferences and Gary Holloway is very clear in pointing this out. The numerical value is an “indication” of certain aspects and even a diamond that rates below a “2”, can have poor visual appeal. We should always revert conversations back to the superlative craftsmanship of each and every diamond we sell and our marketing material continually emphasizes this point. Consistency is a big part of what we do, and our customers can rest assured that the makes of our diamonds do not factor in to the value equation of choosing a diamond.