Sink like a stone without you

Next door to my station, a former sandwich shop has been turning into something else. Today it's got its pink-and-black fascia up. It's called "Afters", and helpfully lists what it will purvey:

Coffee
Gelato
Crepes
Frozen yogurt
Cold stone
Waffles

Err.... a nice cold stone for afters, anyone?

(I'm familiar with places advertising "hot stone" pizzas or steaks, but I have absolutely no idea what they mean here...)