I created a new line of rings, using the "mica effect". It's very complicated to explain for me :), what it is exactly, so I borrowed a good explanation from the best collection of clay techniques, the Glass Attic:
"The metallic clays contain small flat flakes of mica, which after manipulation allow them to appear as either of two tones of the basic color used. If the particles in the clay have been "aligned" (with all their wide sides flat and facing the same direction), light is reflected from the clay in that area and it will appear to be very bright, shiny and pearlescent. If, however, the mica particles are randomly distributed thoughout the clay, or if the aligned clay is placed on its side so that what's seen is the edges of all the flakes, very little reflection will occur and that area will appear darker, dull and not pearlescent."