查塔姆助熔剂法合成红宝石──具暗色核心的新品种

CHATHAM FLUX-GROWN SYNTHETIC RUBY:A NEW VARIETY WITH DARK COLOURED CORES

一种具暗色核心的助熔剂法合成红宝石近期由查塔姆公司推向珠宝市场。它表现出的特征是内部缺乏助溶剂残余物，并普遍发有暗色核心。测试结果表明，这种合成红宝石内部多发育完美的几何时称生长分区结构、相间分布的六边形暗色薄层及具分带结构的暗色核心。紫外光区内0^(2-)－Fe(3+)荷移带吸收边＜230nm，且荷移带吸收尾部＜320nm．研究认为，该红宝石在生长过程中由于物化条件的变更和Cr，Ti杂质元素的不均匀局部聚集，是导致其暗色核心形成的主要缘由。

A variety of Chatham flux-grown ruby with the dark coloured cores developed by the Chatham Company is available in gem markets recently. The internal feature of this stone is character-ized by the absence of the flux residues and by the Seneral growth of the dark coloured cores. The study shows that Chatham flux-grown ruby has well-developed symmetry growth zoning structure, which is the thin hexagonal layers distributing alternatively and the black core with zoning structure. The absorption edge of the O^(2-)-Fe^(3+) charge transfer band within the ultraviolet zone is smaller than 230 nm.In addition, the absorption tail of this charge transfer band is smaller than 320 nm. It has been concluded that the change of the physicochemiCal condition and the heterogeneous local concentration of impurity elements of Cr and Ti during the growth process of the ruby are the main causes for the formation of the dark coloured cores.