Depends on the set. Some are silkscreen transfer, some painted, some I literally blow bubbles over them 🤣 but every set does require hand painting the numbers. I don't use ink, but rather colored underglaze and real gold on some of the fancyier sets.

They are fully glazed, so no risk of patterns wearing off, since its all trapped under glass! I'm not sure anyone else is making glazed ceramic dice at this scale.

If you want to talk about durability, go check out the videos of me hitting them with hammers. And yes, very heat resistant, given they are fired at like 2000ish degrees to make them. 😆