The courtyard was paved with weathered bluestones that gleamed softly in the sunlight.

bluestones 是复合名词，由 blue（蓝色）和 stones（石头）组成，字面意思是"蓝石头"。这里特指一种天然青灰色石材，常用于铺路或建筑，表面因长期风化会呈现出独特的蓝灰色光泽。