A box crystal is one of several shapes a watch crystal can take, alongside flat and domed. It can be made in sapphire or in mineral glass. One retailer says a box-style sapphire crystal cuts down distortion. The same retailer says it also improves how the watch looks.
Why does TAG Heuer call it a glass box?
TAG Heuer explains the name in two parts. The sapphire is the glass. The raised dome makes the box. The crystal is a new type of domed sapphire, developed by the brand for its 39 mm Carrera case. Its shape copies the plastic crystals fitted to Heuer Carrera chronographs in the 1960s. That way, the modern watch keeps the look of those watches while using a different material.
What is a box crystal made of?
Box is a shape, not a material. The same shape can be made in different crystal materials. Seiko’s Hardlex, a mineral glass, is one example. Sapphire is another, as TAG Heuer’s Carrera shows. Watches from Grand Seiko have box crystals too. When looking at a watch, shape and material are two separate questions. One sets how the crystal looks. The other sets what it is made from.
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