Quote:
Originally Posted by chrisny
I thought one of the reviews I saw said they were not crystal, just plain glass. Don't recall who did that particular review, but wanted to point out in case that matters to anyone, may want to confirm.
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Actually, it's hard to track down what it's really made of. It's been referred to in multiple reviews, particularly early reviews, as Swarovski crystal (and nothing from BMW or Swarovski confirms), so much that "crystal" has become the default moniker. BMW only specifies "glass" controls. But fact is, crystal and glass are somewhat interchangeable. All crystal is glass, but not all glass is crystal. "Ordinary" glass is an amorphous solid (mostly silicon dioxide with metallic carbonates), while crystal is, well, "crystalline" glass (atoms and molecules arranged in an ordered three dimensional lattice), made by the addition of various minerals. As far as physical properties, glass is actually stronger than crystal because of its uniformity. The EU has very specific requirements for glass to be called crystal (largely ignored - lead 24%, density 2.9, refractive index 1.5+), while in the US any glass with more than 1% lead content can be properly termed crystal, although the generally accepted requirement for leaded crystal is at least a 24% lead content. And then there is "lead-free" crystal (added metallic oxides other than lead). So as far as the actual composition of the "glass" controls in the X5 (and X7), the answer likely is "it's complicated."