Stevensons-Stone® is a Jesmonite based product.
Jesmonite is a rapid setting acrylic polymer modified cement based composite. It is a shrinkage-compensated material of low permeability and is durable in all conditions of external weathering.
The compound is alkali free and as such is free from the efflorescence associated with ordinary Portland cement based systems. The product contains a fine decorative aggregate and powder pigments, carefully controlled to give a consistent decorative surface finish after treatment with a proprietary brick cleaner or acid etch.