2 oz / 57g block of N983 Nature Granite - the lighter of the three grey stone-effect shades in this range, pale enough to use as a base for mixing other stone-effect colours too.
Cernit polymer clay Nature is a range of stone effect clays, with 2 grey shades and 4 other colours.
The clays contain fibres and other inclusions that mimic the look of stone very effectively. Because of the fibres, they are not really suited to techniques where precise slices must be taken, such as Mokume Gane or millefiori caning. However, they come into their own with modelling, moulding etc. and like all the cernit clays, you can further embellish the clay with paints, inks etc.
Cernit is Phthalate-free, easy to use and very strong when baked, even in thin sheets. Bake for half an hour at 110 - 130 degrees C.