How to rate symmetry

I'm designing an interface where the user needs to rate the symmetry of 2 objects.

The ratings are:

1 means not symmetrical and 5 means very symmetrical.

Currently, it has a star rating. However, the star icon suggests quality, and I don't want the user to think that a symmetric pair is better an asymmetric one.

How can I allow people to rate symmetry without relying on star-ratings?