Bro that was an absolute accident. It's my gen 16710 with aftermarket insert and clasp (I know, who does that, right?). I was just taking some studio type pics and didn't even notice the dial color. It's a crystal reflection off my blue shirt. After I saw it in some pics, I took more with the reflection evenly spread to capture this look.
If you want a real blue dial, it's likely going to have to be a 6 digit one.
As a side note I recently took a marker off two different 6 digit GMT dials in hopes of converting one to a 5 digit dial. In both cases the glue residue and slight dial scratches and depressions, etc would have been visible with a smaller diameter marker installed. So I gave up on that notion.