Authenticating suspected Burmese ruby vs synthetic corundum — anyone have hands-on experience with the inclusion patterns?

I have a stone I am looking at for a client — submitted as a natural Burmese ruby, approximately 2.8 carats, vivid red with strong fluorescence. Under the microscope I can see fluid inclusions and some needle-like rutile structures, but the distribution pattern is not quite what I expect for Mogok material. The stone also has unusual clarity for a natural ruby of this size. I have done the RI check (1.762/1.770), specific gravity is in range, and UV response is strong red under SWUV. No obvious signs of fracture filling or heat treatment visible. My concern is that advanced synthetic corundum (particularly Chatham or Kashan) has gotten very good at mimicking natural inclusion patterns. Does anyone here have direct comparison experience between Chatham ruby inclusions and Mogok natural inclusions under 40x? I am going to recommend the client send it to GIA regardless, but I want to form my own opinion before writing my prelim assessment.