From a metre away, natural stone and cast gypsum look alike. Up close, the difference is weight, workability and where each one belongs.
Weight
A 20 cm cast disc weighs about 900 g. The same footprint in 20 mm granite weighs close to 5 kg. That gap decides handling, shipping, and whether a piece needs a reinforced support.
Workability
Stone is cut and polished; gypsum is poured and demoulded. Casting lets you place the aggregate where you want it — chips near the surface stay visible, chips deeper down stay buried — and you can do it at home in a silicone mould.
Where each one belongs
Stone wins outdoors, under load, and anywhere a scratch must not show. Cast gypsum wins for interior objects: trays, coasters, vases, dishes. It is neither structural nor frost-proof — sealed, it takes everyday indoor use; unsealed, it stays chalky and marks.
The honest trade-off
Cast pieces are lighter, cheaper and repeatable. They are also softer: a dropped tray can chip. If that matters to you, buy stone. If you want the mineral look in objects you make yourself, cast it.