Ammolite Polished 2.3" Green Blue Slab Specimen #LV8757Size: 2. 3", Approx. 44g A crystal slab is a piece of crystal cut into a flat shape, often with natural, unpolished edges. The flat shape makes it easy to display upright on a stand or lay flat on the body. Slabs can show off a crystal's pattern and colors sometimes better than a freeform or tumbled stone as there is more smooth, contiguous surface to look at.