Have a heart of gold

形容人非常可靠且好心的。

Peter has a heart of gold if you give him the chance to prove himself.

如果你给他一个机会证明自己，皮特会非常可靠的。

You can trust her. She has a heart of gold.

你可以相信她。她非常靠谱。

Have a heart of stone

形容人冷漠、记仇。

如果说上面一条“a heart of gold”是金子一般的心，那“ a heart of stone”就是它的反面——铁石心肠了。

She'll never understand your position. She has a heart of stone.

她永远不会明白你的处境。她是个铁石心肠的人。

Don't expect any pity from me. I have a heart of stone.

不要期望从我这儿得到任何怜悯。我就是一个冷漠无情的人。