Stone coasters are chosen from a photograph and lived with for years. Here is what the photograph does not tell you.

The one trade-off everything else hangs off

Porous stone absorbs. That is why a sandstone coaster makes the ring vanish, and it is why the same coaster keeps the first glass of red wine for ever.

Dense stone does not absorb, so it does not stain and it does not etch — and the condensation stays on the surface. Choose which failure you would rather have. There is no third option, whatever the listing says.

Marble is the one that surprises people

Marble is calcium carbonate. Acid dissolves it. Lemon, lime, wine, vinegar and cola all leave a dull matt patch where the polish used to be, usually on first contact.

That is an etch, not a stain, and the distinction matters: a stain is something in the stone, an etch is stone that is no longer there. It cannot be cleaned off, only repolished. Buy marble for boardrooms, gifts and hotel rooms; buy granite or slate where cocktails are poured.

Slate is split, not sawn

Natural slate splits along its own cleavage planes, which is what gives it the riven face and why thickness varies slightly across a batch. That variation is the material.

Laser etching works beautifully on it, because removing the dark weathered surface exposes paler stone underneath — a permanent change to the rock rather than a coating. It is the best-value engraved stone in the category.

Ask about the backing and the groove

Full-coverage cork or felt, not four dots. Stone is harder than any table finish, and a bare edge with grit under it will mark a lacquered surface.

On granite, ask for a slightly recessed face or a drip groove. Without one, the condensation has nowhere to go and the coaster lifts with the glass.

Put freight on the quote

Stone is heavy and granite is roughly twice the weight of slate for the same size. On a thousand-set gifting run, freight can be larger than the price difference between the two stones you were comparing.

It belongs on the quote before you decide. Almost nobody puts it there.