This clay tends to darken at high temperatures. Wet-sand and buff the piece. Pieces finished this way look more translucent than pieces finished with a gloss glaze. This particularly enhances the translucency of tinted clay. You can also use glass marbles or stones as a transparent element of your design along with the clay.
Transparent clays can develop tiny flaws while firing.
Some artists seek out this effect, because it can be used in faux stones to make the pieces look more like natural stone. On the other hand, if you want the plaquing effect, you can enhance it by putting your pieces into a preheated oven and removing them as soon as firing is complete. Wet-sanding and buffing will also make the plaquing more visible.