Reticulation is a process used on sterling silver to achieve an organic textured quality. The silver is heated with a strong blow torch until it begins to melt. When the surface of the metal becomes molten the force of the blow torch causes the metal to flow, when the torch is pulled back and the metal cools, ripples and ridges are left.
This is an unpredictable technique, it's impossible to get exactly the same results twice. This makes it's really fun to do! You never quite know how a piece will turn out. Any further embellishment (setting of stones or adding layers) has to be improvised a bit - you have to work with the shape and pattern you have created.