Moser has blown, cut and engraved crystal in Karlovy Vary since 1857, supplying the Austrian imperial court and, after it, half the courts of Europe and the Near East. The metal is lead-free potassium-calcium crystal — harder than lead glass, and cut deeper because of it, which is why a Moser piece carries oak leaves and stags sunk into the wall rather than scratched onto it.

What the house is actually known for is colour: alexandrite, beryl, topaz, rosalin, aquamarine, eldor, oceanite, smoke. Alexandrite is dichroic — soft lilac under one light, bright azure under another. This system is built on that behaviour: a saturated transparent ground, gilded hairlines where facets meet, and a primary that changes colour when you touch it.