Acrylic / Plastic / Plexi
Common terms for plastic watch crystals. “Plexi” is a common shorthand (often used generically). Acrylic can be polished and is less likely to shatter than glass, but it can scratch.
Crystal
The clear cover over the dial. For acrylic, this is typically a molded piece pressed into a case seat or bezel.
Bezel
The ring around the crystal. On many watches, the bezel is the part the crystal presses into or under.
Case Seat / Crystal Seat
The machined ledge or opening in the case (or bezel) that the crystal fits into. This is the area you typically measure for sizing.
Press Fit / Friction Fit
A fit that relies on tight tolerances and compression. The crystal is pressed into the seat and held by mechanical retention (no adhesive required when properly sized).
Snap Bezel
A bezel that snaps on/off the case. Some snap bezels clamp or retain the crystal when installed.
Tension Ring / Armored Crystal
An acrylic crystal with an internal metal ring. The ring adds stiffness and can help stabilize the dial edge on certain cases. It can also slightly reduce visible dial area.
Chapter Ring / Rehaut
A ring near the outer edge of the dial (sometimes with minute markings). Important for fitment because it affects available clearance and how a tension ring crystal might sit.
Step Crystal / Shouldered Crystal
A crystal with a defined “step” (shoulder) that seats at a specific height. Used when the case requires a crystal to sit on a ledge rather than relying only on the skirt.
Skirt
The lower vertical wall of the acrylic crystal that engages the seat. This is the part that compresses during installation on many press-fit styles.
Dome / Domed Crystal
A crystal with a curved top profile. Dome height affects appearance and clearance.
Low Dome / High Dome
Describes dome height. Higher domes can provide more clearance for tall hands or dial features.
Flat Top
A crystal with a relatively flat upper surface (may still have slight curvature). Often used where clearance needs are minimal or a flatter profile is desired.
Edge Bevel / Chamfer
A slight angled edge on the crystal profile. Can affect how it seats and how it looks at the bezel line.
Hand Clearance
The vertical space between the top of the hands (often the seconds hand or chronograph sweep) and the underside of the crystal. Insufficient clearance can cause rubbing or stopping.
Dial Furniture
Raised dial elements like applied markers, logos, or thick lume plots that can require additional clearance.
Crystal Press
A tool that applies even pressure with shaped dies to install crystals without cracking or distorting them.
Dies
Interchangeable press attachments used to match the crystal/bezel shape. Using the wrong die can chip the bezel or crack the crystal.
Out-of-Round
When the case opening is slightly oval instead of perfectly circular. This can affect fitment and cause inconsistent measurements.
Burr / Corrosion in Seat
Small rough spots or corrosion in the crystal seat that can prevent a crystal from starting or seating evenly.
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