Alexandrite is the colour-change variety of chrysoberyl, typically shifting from green to bluish green in daylight to red to purplish red under incandescent light. Commercial alexandrite is sourced mainly from Brazil, Sri Lanka, and East Africa, with the Russian Urals important historically.
Violet quartz earns its place in both jewellery and mineral collections through colour rather than rarity. The appeal of amethyst lies in how evenly or intensely that purple is distributed, from pale lilac material to richly saturated stones cut for statement pieces.
Tanzanite is one of the few gemstones whose identity is closely tied to a single modern locality. Its blue-to-violet colour and pleochroic character give it an instantly contemporary profile among transparent jewellery stones.