Inspection begins with an unambiguous drawing
Quality is easier to control when acceptance criteria are agreed before machining.
A sapphire watch structure may contain optical surfaces, decorative surfaces, hidden interfaces, threaded hardware zones and thin edges in one part. Applying one generic cosmetic rule to the entire component can increase cost without improving function. We work with customers to classify critical features and define how each will be inspected.
Dimensional control
Critical diameters, cavity dimensions, hole positions, steps, wall sections, parallelism and assembly interfaces are measured from agreed datums.
Visual inspection
Polished areas are evaluated for scratches, pits, chips, haze and visible inclusions under agreed lighting and viewing conditions.
Fit verification
Where samples or mating components are available, prototype fit can be checked before the project advances to batch production.
Recommended drawing structure
- Functional datums and measurement references
- Critical-to-fit dimensions and tolerances
- Cosmetic zones ranked by importance
- Allowed edge exclusion near contours and holes
- Surface finish symbols or written requirements
- Color reference and matching method
- Inspection report requirements
- Packaging and cleanliness expectations
Typical inspection flow
Incoming material → in-process geometry → pre-polish review → final dimensions → cosmetic inspection → fit check when required → cleaning and protected packaging.
The exact flow is adapted to the geometry and the risks identified during DFM review.
Key quality categories
| Geometry | Overall size, cavity, wall thickness, steps, shoulders, holes and positional relationships |
|---|---|
| Form | Flatness, roundness, concentricity, parallelism or profile where specified |
| Surface | Polish, ground or frosted finish; scratch and pit limits for designated zones |
| Edges | Chips, chamfer width, radius continuity and transition quality |
| Appearance | Clarity, color, shade matching and inclusion limits under controlled viewing conditions |
| Assembly | Clearance, alignment, fastening interface and reference-component fit |
| Records | Dimensional report, material information, images or other documents agreed for the project |
Cosmetic inspection must be measurable
Terms such as “perfect,” “flawless” or “luxury quality” are not inspection standards. A workable cosmetic specification should state the viewing distance, light source, background, observation time, magnification if any, and whether different surfaces have different limits. This reduces subjective disputes and keeps the quality plan aligned with the real visual experience of the assembled watch.
Packaging is part of quality
Finished sapphire parts should not contact each other. We use separated protective packaging appropriate to polished surfaces and vulnerable edges. Special cleanliness, labeling or lot-separation requirements should be stated in the RFQ.
Frequently asked questions
Can you provide dimensional inspection reports?
Yes, reporting can be aligned to the critical dimensions agreed for the project. State the required format and sampling level before quotation.
How should cosmetic zones be marked?
A color-coded drawing is effective: identify primary visible surfaces, secondary surfaces and hidden functional interfaces separately.
Can every tolerance be held equally tightly?
No. Tolerance capability depends on size, geometry, datum access and processing sequence. Tighten only features that control function or appearance, then confirm feasibility during DFM.