为什么钻石颜色等级从D开始标记?

　　henduoxiaofeizhechucijiechuzuanshi4cdengjideshihou，duiyansedengjicongdkaishibiaojidoudahuobujie，weishenmezuanshi4cdengjizhongdeyanseshicongdkaishi？a、b、cshiganshenmede，naquleni？

　　weishenmezuanshiyansedengjizuigaocongdkaishi？qishizuanshide4cdengjibiaozhunshiyoumeiguobaoshixueyuan(gia)suochuangjiande，zaigiadedzhizdefenjixitongshangweituiguangqian，zuanshixingyeyonggezhonggeyangdefuhaobiaoji， youdeshiyonga、b、cji，dandingyibuqing， youdezeyongshuanga(ruaa)， yeyouqitaxitongshiyongalaboshuzi(0、1、2、3)huoluomaziⅰ、ⅱ、ⅲzuojishude。 haiyouxiexitongzecaiqumiaoshushideziyan，ru「lanbaiblue-white」huo「youzhibaifine white」，zheileizuihunxiaodezicifeichangdebujingque，jingchanghuidaozhifashengwudao。 suoyigiazhidudechuangshirenmenxiwangyouxindekaishi，buxiwangheqianshubuliangxitongjianyourenheguanlian，yinciyidzuoweizhidudeqishi。

　　zuanshiyansedengjiweiheyidjikaishibiaoji？chuleshangmianzheiyizhongshishuofawai，hailiuchuanzheqitasizhongshuofa，womenlaikanyixia：

　　yi、dshizuanshiyingwendediyigezimu，suoyicongdkaishi；

　　er、giajianceyanseshiyongdebiseshimeiyoudsede，biesebiseshigaodezuanshijiushid se；

　　san、giachuangshizhe jihourenliuleyudi，liule a、b、c se yibeifaxianbidsegengtougengbaidezuanshishishiyong；

　　si、youyuyushiyeshibaoshideyizhong，ertongchangyushidepinzhidoubeifenweia、bhechuo，weilebuyuzuanshifashengfenqi，suoyijiuyidseweiqidian；

　　zuanshiyansededengjijiuweihecongdkaishidegushijiushiyishangjigeyuanyinle，gengduozuanshichangshidexiangguanzixun，qingguanzhuwoaizuanshiwang。