The hallmark of something or someone is their most typical quality or feature.
双语例句
例：
It's a technique that has become the hallmark of Amber Films.
这是一项已成为安伯电影公司标志的技术。
2.?[C 可数名词] （金银等制品上的）标记
A hallmark is an official mark put on things made of gold, silver, or platinum that indicates the quality of the metal, where the object was made, and who made it.
双语例句
例：
Early pieces of Scottish silver carry the hallmarks of individual silversmiths.