The present disclosure describes architectural blocks configured to give the appearance of real cut stone. A plaster composition may be applied to one or more surfaces of a block, such as a concrete masonry unit (CMU) to form an architectural block having the appearance of cut stone. The plaster composition includes a cementitious component, such as white Portland cement, a limestone aggregate component, and optionally an adhesive component. The limestone aggregate component includes a fine sand portion and a coarse sand portion that effectively enable the appearance of cut stone after finishing of the plaster surface via sanding and/or polishing.