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This is a generic sapphire crystal designed for the Franck Muller Conquistador Cortez 10900 watch, featuring a square tonneau profile with dimensions of 31.8mm × 31.8mm × 2.8mm × 1.0mm (length × width × overall height × edge thickness). Made from synthetic sapphire (Mohs hardness 9), this aftermarket replacement crystal offers exceptional scratch resistance and optical clarity, restoring the watch‘s distinctive Conquistador aesthetic when the original becomes scratched or damaged.
About the Franck Muller Conquistador Cortez 10900
The Franck Muller Conquistador Cortez collection features a distinctive tonneau (barrel-shaped) case with a bold, sporty aesthetic. Key specifications of the original watch include:
| Specification | Details |
|---|---|
| Collection | Conquistador Cortez |
| Reference | 10900 |
| Case shape | Tonneau / Square |
| Water resistance | 30m / 3 ATM (typical) |
| Crystal | Sapphire (original) |
Important Note on Dimensions
The 31.8mm × 31.8mm measurement indicates a square/tonneau-shaped crystal – this is not a round crystal. The 2.8mm overall height reflects the domed profile, while the 1.0mm edge thickness allows the crystal to integrate seamlessly into the case design. Always verify your original crystal dimensions before purchasing.
The sapphire crystal serves as the protective cover for the dial. Proper care ensures longevity:
Cleaning: Use a microfiber cloth to remove fingerprints and smudges. Avoid harsh chemicals or abrasive materials that could damage any anti-reflective coating.
Avoid Impact: While sapphire is highly scratch-resistant (Mohs 9), it is still susceptible to cracking under sharp impact. The square/tonneau profile is particularly vulnerable at the corners.
Regular Inspection: Periodically check for chips or cracks, especially around the edges where the crystal meets the case. Even small damage can compromise water resistance.
Water Resistance Reminder: The original Conquistador Cortez has limited water resistance (30m/3 ATM) – suitable for everyday splashes but not for swimming or showering. After any crystal replacement, professional water resistance testing is recommended.
CRITICAL WARNING: The Franck Muller Conquistador Cortez has a distinctive square/tonneau case. Crystal replacement requires specialized tools and expertise. Improper installation can crack the crystal or damage the case.
Tools Required:
Crystal press with appropriate square/tonneau-shaped dies
Case back opener
Movement holder
Non-metallic tweezers
Dust blower
Crystal gasket (MUST be replaced with a new one)
UV glue (if adhesive-fit type)
Lint-free cloth and finger cots
Digital caliper (for verification)
Step-by-Step Installation:
Step 1: Remove the Old Crystal
Open the case back using an appropriate case back opener
Carefully remove the movement from the case
If the old crystal is cracked, cover it with tape to prevent glass fragments from scattering
Use a crystal press with a die slightly smaller than the crystal dimensions (31.8mm × 31.8mm) to press the old crystal out from the inside of the case
Step 2: Clean the Case
Thoroughly clean the crystal seating area using isopropyl alcohol
Remove the old crystal gasket completely—the gasket must be replaced every time the crystal is removed
Inspect the case for damage or corrosion
Pay special attention to the square/tonneau case corners
Step 3: Prepare the New Crystal
Inspect the new 31.8mm × 31.8mm sapphire crystal for any defects, chips, or scratches
Clean both sides of the crystal with a lint-free cloth
Note the orientation – the domed side faces outward
Step 4: Install the New Gasket
Install a NEW crystal gasket into the case recess
The gasket is critical for water resistance—never reuse an old gasket
Ensure the gasket is seated evenly without twists, especially around corners
Step 5: Install the New Crystal
Place the case face-up on the crystal press base
Position the new square/tonneau-shaped crystal onto the case, ensuring it is centered
Use a crystal press with an appropriately sized square/tonneau-shaped die
Apply steady, even pressure to seat the crystal
Ensure even pressure distribution on all corners
Step 6: Reassembly and Testing
Reinstall the movement into the case
Close the case back with proper torque
Professional water resistance testing is recommended after installation
Important Notes:
The Franck Muller Conquistador Cortez has a distinctive square/tonneau case – square/tonneau crystals are more difficult to install than round ones
Professional installation by a watchmaker experienced with Franck Muller is strongly recommended
Common Reasons for Crystal Replacement:
| Reason | Description |
|---|---|
| Scratched crystal | Despite sapphire’s hardness, scratches can occur from contact with diamond or abrasive materials |
| Cracked or shattered | Impact damage from dropping the watch – square/tonneau crystals vulnerable at corners |
| Chipped edges | Damage around the crystal perimeter, often from improper removal |
| Cloudy or delaminated | Anti-reflective coating deterioration over time |
Diagnostic Process:
Visual Inspection: Under magnification, examine the crystal for scratches, chips, or cracks. Pay special attention to corners where damage is most common.
Water Resistance Check: If the watch has been exposed to water or shows signs of fogging, internal damage may have occurred.
Movement Check: For watches with cracked crystals, inspect the movement for glass fragments or moisture damage.
Step-by-Step Repair Process:
Assessment: Examine the old crystal to determine the cause of failure. Check the case for any deformation that might affect the new crystal fit.
Case Preparation: Thoroughly clean the crystal seating area. Remove all old gasket material and debris.
Gasket Replacement: Always install a NEW crystal gasket.
Dry Fit Test: Before final installation, test-fit the new square/tonneau-shaped crystal to ensure proper seating.
Installation: Follow the installation instructions above. Pay extra attention to even pressure on all corners.
Quality Check: After installation, inspect for even seating and absence of gaps.
Water Resistance Test: Perform professional water resistance testing to verify the seal.
When to Seek Professional Help:
You lack a crystal press or appropriate square/tonneau-shaped dies
The case shows signs of damage or deformation
The watch requires water resistance testing equipment
The watch has significant monetary or sentimental value (Franck Muller is a luxury brand)
You are uncertain about proper orientation for the square/tonneau-shaped crystal
Preventive Maintenance:
Professional service every 3-5 years recommended
Regular inspection of crystal and gaskets
Avoid exposing the watch to water without proper water resistance testing
Have the watch serviced by professionals familiar with the Conquistador case design
Q1: What is the size of the original Franck Muller Conquistador Cortez 10900 case?
A: The original Franck Muller Conquistador Cortez 10900 features a tonneau (barrel-shaped) case. The 31.8mm × 31.8mm measurement in this listing refers to the crystal dimensions, not the case size. The watch typically has a water resistance rating of 30 meters (3 ATM) .
Q2: Is this a square or round crystal?
A: This crystal has a square/tonneau-shaped profile measuring 31.8mm × 31.8mm. It is designed for the square/tonneau case of the Franck Muller Conquistador Cortez. This is not a round crystal – verify your original crystal shape before purchasing.
Q3: Is sapphire crystal scratch-proof?
A: No crystal is completely scratch-proof. Sapphire crystal has a Mohs hardness of 9, making it highly resistant to scratches from everyday objects (steel is ~5.5, glass is ~6). However, it can still be scratched by diamond (hardness 10) or materials containing corundum. It is also susceptible to cracking under sharp impact – the square/tonneau profile of the Conquistador crystal is particularly vulnerable at corners.
Q4: Can I install this crystal myself?
A: Not recommended. The Franck Muller Conquistador Cortez has a distinctive square/tonneau case that requires specialized tools (crystal press with square/tonneau-shaped dies, case back opener) and expertise. Square/tonneau-shaped crystals are more difficult to install than round ones due to the need for even pressure distribution on corners. Professional installation by a watchmaker experienced with Franck Muller is strongly advised.
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