Some examples of (adjectival) usage, with commentary:
"She's my dearest friend." ("Dearest" is typically used to describe a person whom one is closest to.)
"This is the finest example of pre-Columbian pottery that has ever been found" "Our police force is composed of the city's finest individuals." ("Finest" can be used to describe people or things that one regards as the
These words are all superlatives. They have different meanings.
I sent a love letter to my dearest sweetheart. We set the table with the finest china. The boat sails over the deepest ocean. We like the warmest weather.