Hi Maizi,
These images are macro shots that make it easier to see what the original poster was trying to diagnose. The Form 4 has dimensional accuracy within ±0.15% (lower limit of ±0.02mm). Clear parts can also exaggerate tiny surface details because of how light refracts through it, but can be post processed with polishing, or clear coating.
Here are a few more of my favorite examples of Clear Resin being post processed:
