马达加斯加蓝色蓝宝石的颜色特征

为了了解马达加斯加蓝色蓝宝石的颜色特征，采用GemDialogue颜色系统对其进行了描述与分级。对比世界上主要产地（澳大利亚、斯里兰卡、柬埔塞、缅甸）蓝宝石的颜色特征发现，马达加斯加蓝色蓝宝石样品的黑色罩过高，使得其最终的颜色等级大多在1～4范围内，属于“商业级”。为了进一步确定马达加斯加蓝色蓝宝石样品的颜色特征及其与全Fe，Ti质量分数的关系，采用紫外一可见光分光光度计和电子探针测试了样品。结果显示，随着全Fe与Ti质量分数的增加，样品的蓝色加深；当蓝宝石样品中全Fe的质量分数为0．02％～0．75％、Ti的质量分数为0．006%～O．040％且其全Fe与Ti质量分数比值为10～30时，蓝宝石样品的颜色为纯正蓝色；当超出此范围时，蓝宝石样品通常含有绿色或紫色色调。

Colour Characteristics of Blue Sapphire from Madagascar

In order to investigate the eolour characteristics of the blue sapphire from Madagascar, the GemDialogue systerm is used for describing and grading the blue sapphire samples. Comparing with the sapphire samples from Australia, Sri Lanka, Kampuchea and Burma, the colour characteristics of the blue sapphire samples from Madagascar are blue with a little high black colour mask, in the range of 1-4 colour grade, which belong to the comercial grade. In order to determine the relationship between its colour and the contents of total Fe and Ti, UV-VIS spectrophotometer and electro microprobe are used to analyse the samples. The results show that the blue colour of the sapphire sample changes to darker as the contents of total Fe and Ti increase. The blue colour of the sapphire sample is more pure as the content of total Fe is 0.02%-0.75%, the content of Ti is 0. 006%-0. 040% and the content ratio of total Fe to Ti is 10-30. When more than these ranges, the colour of the sapphire sample is usually green or purple hue.