钻石是珍贵的宝石。

A diamond is a precious ___gemstone.

这颗蓝宝石是我祖母传下来的珍贵宝石。

This sapphire is a precious ___gemstone passed down from my grandmother.

这件古董花瓶是我们博物馆的珍宝。

This antique vase is a ___gem of our museum's collection.