Finally the result ! The bronz pebbles survived the oven ! You can see on the small picture how they came out of the oven. In the big picture they are already polished.
However the ring didn't survive, it didn't break but it ripped. Whit a lot of patience I can repear it.
It shrunk about 5 sizes in the oven. The ring with the 'ankh' is for my daughter.