A dark area appears at an oblique angle in a single photograph. Does that establish a coating difference?
| Field | Scope |
|---|---|
| Subject | Crystal reflections: why a dark patch is not a coating test |
| Exercise | Discuss the stated question; distinguish sources, interpretations and unresolved points. |
Clarification for “Crystal reflections: why a dark patch is not a coating test”: the point beginning “No single lighting setup settles…” belongs to the question as written. It should not be read as a report that a new check, purchase or experiment has been completed. Review focus: scope. Keep the stated question separate from any broader claim.
No single lighting setup settles that question. Compare multiple controlled angles and describe the visible observation without asserting material specifications that have not been verified.