| 和红宝石一样,选购祖母绿颜色是最重要的,以纯正的翠绿色最为名贵,过淡或过深对其价值都有影响。祖母绿多有瑕疵,但不能有明显的裂纹。除了考虑上述基本条件外,不同产地的祖母绿价值差别很大,如巴西祖母绿每克拉仅值10-12美元,而哥伦比亚的优质祖母绿每克拉平均为400-600美元,重量在10克拉以上的,每克拉竟可超过1万美元,即高出巴西祖母绿的40位以上。国内珠宝市场常有低档祖母绿蛋形光身戒面出售,系我国云南所产,透明度较差,大都有微裂纹,为了掩盖裂纹, |
| 常用雪松油或人工合成的液状环氧树脂浸渍。此外,还有人工合成的祖母绿,与天然祖母绿很难区别,因此鉴别祖母绿的难度很大,如购买价格昂贵的祖母绿首饰,最好应有珠宝检测单位的鉴定证书,以防吃亏上当。 |
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钻石的 4C标准
威四选用4C标准最完美配合的钻石。4C 为评定钻石价值的四个主要准则,代表色泽(Colour)、净度(Clarity)、克拉重量(Carat weight)及切割车工(Cut)。
色泽
色泽是决定钻石价值的主要因素之一,钻石愈接近无色愈见珍贵,价值亦因而愈高。业内评定色泽的指针以英文字母D开始标示钻石色泽,由D级透明无色钻石,一直排至Z级的淡黄色钻石。
除特别选配的彩色钻石外,威四 婚嫁系列所用的单颗镶嵌钻石,全为D及E级的 无色钻石。
净度
每颗钻石净度由其内含物(内里杂质)及瑕疵(表面不平整)的数量、大小、性质及位置所影响的光线折射程度而定。
如在业界专用的10倍强力放大镜下钻石并无明显内含物或瑕疵,即可获鉴定为无瑕。大部分 钻石均有一定程序的瑕疵,影响钻石净度。
净度分级标准由最佳的无瑕(FL)依次排列至有明显瑕疵(13)级别。
威四所用之钻石,全为净度介乎IF至VVS2等级的上佳钻石。
克拉重量
克拉为国际自1907年起计算钻石重量的统一单位,1克拉相等于0.2克。钻石价值以指数方式随克拉重量上升而增加。除钻石体积外,其罕有度亦说明其价值所在:愈大颗的原石在自然界愈罕有,因此两颗半克拉的钻石远较一颗一克拉钻石便宜。0.2克拉或以上的钻石均属罕贵。 |
| 庆伯利国际钻石原石认证标准机制(KPCS)于2003年成立。认证标准钻石贸易,藉以确保于市场上沽售的原石。 |
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