One can give a name just to something one is aware of.
One can become aware of different things – planets, persons, hurricanes and so on… So one can give a proper names to them.
One can also become aware that multitude of things have or might have some similarity. So one can give a common name to those objects that have such similarity. For this thing we use common nouns.
As far as giving a common name goes, in principle there is no difference between artifacts and natural kinds. In both cases we have to become aware of some multiplicity of things sharing certain similarity.
The basic similarity that is first noticed is gestalt perceptual similarity. In gestalt similarity one thing reminds you on another thing, even without explicitly being able to describe that thing (or e.g. make a picture of that thing), i.e. without awareness of the details. However, further, one can become aware of the further characteristics of those things, the possibility to use them for different things and so on… To the gestalt perceptual similarity of the named kind, then this other awareness of shared characteristics is added. We can say, that we are now aware of a multitude of things which share not just gestalt perceptual similarity, but also other characteristics.
Because the common nouns relate to the awareness of multitude of things sharing some similarity, they refer to all those things that share this kind of similarity, and not just to the things of which we have become aware of.
This kind of view gives an interesting twist to the twin Earth thought experiment.
The common nouns “water” on Earth, and “water” on Twin Earth in this picture mean same before citizens of Earth and Twin Earth become aware other kinds of similarities among the multitude of the stuff on their planet (i.e. before they become aware that this multitude is chemically analyzable as H2O on Earth, and that it is chemically analyzable as XYZ on Twin Earth).
image by Mor
Tvenice tflooded twith XYZ