Mokume Gane
From the land of the rising sun
Fascinating forging technology
Mokume Gane
Mokume Gane is the name given to a Japanese metal folding technique that is thousands of years old and is not dissimilar to Damascus steel.
The Japanese expression is best translated as “wood-grained metal.” The following pictures and the YouTube video linked below show two ways of making this special technique, which I often use in courses or when making rings in the goldsmith's shop .
In the video I would like to describe a way of making seamless partner rings that are made using the ancient Japanese Mokume Gane technique. There are different paths to the goal and different surface patterns are possible. 
Mokume-Gane is layered material that has been welded together at the boundary layers without solder - diffusion welding. This is made possible by applying high pressure and heat to plates or wires lying on top of each other. In practice, this means that sheets of different materials (combinations of e.g. palladium/red-green-white-yellow gold/silver/copper, alternating around eight to fifteen layers) are heated in a kind of screw clamp in the annealing oven until they touch the The interfaces of the plates fuse and a third, new alloy is created.
Mokume Gane always begins with a so-called module. Normally I make my own material, but in this case I bought it from the companyschichtwerk in Germany. It consists of fifteen layers of palladium and green gold 750/-
The material was delivered in an annealed condition - so it is soft and can be worked on with the hammer fin in the first step.
The hammer blows are intended to compact the material and strengthen the cohesion between the layers
This is what happens on the four long pages...
... with strong blows
Since the material behaves quite well, I decide to twist - twist - the material before the first annealing.
After a few turns the material is annealed...
... and forged further.
On the way to a rod with a round profile, I make sure that no edges fold in. These could unfold again during further processing and disrupt the ring design.
A total of four holes are drilled in the middle on the right and left, as well as in the middle at a certain distance.
They are intended to hold the saw blade so that the bar can be slotted lengthwise.
After sawing, you can start thorning. A work step that must be carried out particularly carefully so that the layers do not come off.
Here the thorning is already more advanced.
At this point I separate both rings from each other.
The ends and the slots inside the rings may be soldered to prevent cracks.
Here at this point the rings are "out of the fire", nothing more can happen. Just a little tapping and filing and adjusting the size.
Here you can clearly see the supporting plumb line inside. This will disappear with further work.
Almost finished.
The ring on the right in the picture is already finished.
The finished rings made of solid gold/palladium - Mokume Gane.
This is just one way to make MG rings. There are many roads leading to Rome and...
These photos are a bit older. Today I no longer buy anything, but make the output modules myself in my workshop. The rings shown here in the photo are rings made of fifteen layers of green gold (75% gold and 25% silver) and palladium.
In one of my courses for Mokume Gane , you can also make materials and rings like this yourself.
In a YouTube video I describe the making of Mokume Gane rings from fine gold and silver.