As Blizzard flies along, he surrounds No'Coure with his huge, slimy tongue and bastes him in a thick coating of saliva. This is to make the next part of what he's doing less painful for him. He swallows down the gem - although the sharp edges are dulled by the saliva all over him. The gem then plops down into his belly next to Jon, but rolls across the floor towards a pool of acid. This is part of how dragons clean their gold and jewels - since their stomach acids are not strong enough to digest the minerals, the digestion simply wears away any dirt on the surface.