Most important is that your shower needs to be built to be converted to steam. Different prep is required for a steam shower. More information is required to respond to your question about herringbone transition. There are multiple ways to transition the tile pattern to ceiling, and a quality tile Pro should be able to show you many options based on your space and tile selections.

To much of a good thing is a bad thing. Skip herringbone used so extensively. Use it selectively, combined with larger tile in the same pattern, from the same manufacturer. No natural sone. Porcelain only.

Be sure that you understand fully how involved doing a steam shower is. It adds another 5-7K to an slready 7-9K shower. It must be vapor proofed. That is beyond waterproofed. The ceiling has to be reframed to have the proper slope. No flat ceilings. You need to factor in the transom glass and ventilation needs. The location of the steam generator has to be planned now. Everything had to be done and planned now.

Agree that all has to be planned out in advance. Disagree that only porcelain can be used in a steam shower. Been doing natural stone steam showers for 30 years. Actual use, maintenance requirements, qualifications of installers and fully educated expectations are important factors when selecting materials. Back on track, Betsy, I think we are suggesting that you may need to consider getting some on-site professional guidance regarding the build itself, then consider the tile selection and pattern.

Great. We never know where these questions are coming from. Put a border at the ceiling and treat it as a separate surface. What's the shower floor?

Here's an example of the border. Obviously not your particular design (herringbone is at ceiling and floor), but notice how we separated the herringbone at the ceiling with the border? Defines that space and eliminates transition issues. Just one thought.