He is an expert in gemology, and he is good at evaluating the quality of diamonds.

Graphology is the study of determining a person's character or condition from their handwriting.

Graphology is a study that interprets a person's character and abilities from their handwriting.

He has expert knowledge.

He is studying computer science at a specialized school.

He is a specialist fool, with no interest in anything outside his field.

He couldn't say anything about issues outside of his field of expertise.

There are many different specialty stores in this town.

Infrared astronomy plays a very important role in the study of the universe.

He was standing at the summit of the mountain.