Spec sheets list sapphire, mineral or acrylic crystals, and opinions in threads are very strong. For a daily-wear watch, what are the real trade-offs, and is an anti-reflective coating worth paying for?
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The core trade-off is scratch resistance versus shatter resistance. Sapphire is very hard to scratch but can chip or crack from a sharp impact on an edge. Acrylic scratches easily but flexes, rarely shatters, and light scratches can be polished out at home. Mineral glass sits in between and is often the cheapest to replace.
Clarifying question: what does daily wear mean for you? Desk work, manual labour or sports change the answer. For desk use, sapphire's scratch resistance is the main benefit. For work with frequent knocks, a slightly domed acrylic that you can polish may last longer in practice, despite the scratches.
Domed crystals of any material add distortion at the edges, which some people like and others find hard to read at angles. Box-shaped or high-domed crystals also add thickness. If you're comparing two otherwise similar watches, check total thickness against crystal profile before assuming the case itself is thicker.
On anti-reflective coatings: inner-surface AR cuts glare without wear concerns. Outer-surface AR improves legibility further but can scuff over time, and the scuffs show up as hazy patches in certain light. When comparing two watches, check which surfaces are coated. Spec sheets often just say 'AR coated' without saying where.