You can not decide either the location or the amount of crystals. The potter is the alchemist that allows the fire to work its magic. In fact it's an organization of the material that passes from one amorphous state to a crystalline complex building, similar to the phenomena of crystallization caused by volcanoes who gave to nature numerous natural crystals, such as those balls of magma called geodes, thanks to a slow cooling, inside the material has time to organize and build crystals.

The body of the piece is in porcelain. It is covered with an enamel composed primarily of zinc, titanium and silica, fired at 1280 C, then we let the oven cool to around 1100 C, at this temperature we must stay for 5 to 6 hours. because it's during this stage that the zinc particles move in the melted glaze to rally around titanium which forms the core to build crystals. The coloring oxides (copper, cobalt, iron, nickel, manganese ...) ,weighed with hundredth of a gram precision, also migrate to the crystals or to the bottom of the enamel for the coloring. Each piece is glazed with special care, few pieces are fired simultaneously in a small hoven to track the cooking's progress.