1.50 Carat Natural Colombian Emerald - 7x7mm Bluish Green Octagon Cut Unset Loose Gemstone for Jewelry Making, Engagement Rings & Custom Designs (优化说明: 1. 核心关键词前置(Natural Colombian Emerald) 2. 补充尺寸单位(mm)和状态(Loose)提升搜索精准度 3. 增加使用场景关键词:Jewelry Making/Engagement Rings/Custom Designs 4. 保留颜色特征(Bluish Green)和切割形状(Octagon Cut) 5. 符合Google SEO的标题长度标准(约60字符+关键信息完整))