I agree with Strange Whimsy in the use of Sculpey Premo Accents for Mica Shift. It is a soft clay and allows for a wonderful alignment of the mica particles in the shift, although the older Premo metallics can work equally as well. It does take a delicate touch when applying slices or shaping beads to prevent a blurring of the shift. Have not done much with colors other than the metallics, but here are two examples of what I have done with this fantastic technique.
This bracelet was done using the older Sculpey Premo Gold and Copper. I combined the colors until I was sure the shift would show well, and then sliced the cane with a modified Mokume Gane method. It turned out amazing shading:
This is a close up of the nugget beads I did for a necklace using the newer Sculpey Premo Accent colors of Antique Gold, Copper and Silver. The cubes are solid shapes after combining the three colors:
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