RE: [Demo notebook] Reference notebook: corrections and recurring beginner questions · RWI-09192

Case 23 — Crystal reflections: why a dark patch is not a coating test

Summary draft for “Crystal reflections: why a dark patch is not a coating test”: the answer addresses “No single lighting setup settles…”; the related point is “Compare multiple controlled angles and describe the visible observation without asserting…”. Keep both connected to the opening question, and mark any conclusion needing further records as unresolved. Review focus: scope. Keep the stated question separate from any broader claim.