What aspect of gem treatment does not involve cutting or polishing?

The focus of this question is on which treatment method does not involve any physical alteration of the gem in terms of cutting or polishing. Among the options provided, enhancing clarity through heat treatment is a method that improves clarity but does not involve cutting or polishing the gem. Similarly, filling cracks with resin and changing the hue with dye are also non-invasive treatments as they do not change the shape or surface of the gem through cutting or polishing processes.

The correct understanding is that all listed treatments enhance the visual appeal of the gem without altering its structure or form through cutting or polishing. Therefore, the option indicating that all of the stated treatments directly improve gem appearance is indeed correct. Each method enhances the gem's qualities through processes that are more about chemical or physical treatment rather than mechanical shaping.