Transparent cobalt, colorless lead glasses; cast (plaster/sand mold), cut, polished, inlaid (sealed with perenator, Bauart-Gefrüt) circle of colorless window glass. Solid blue cone rests on cube of blue cast with interior cone cavity (tip extends almost to base of cube), top of cube has inlaid supporting circle of colorless glass covering cone opening; when lighted, cube appears to have an internal cone mirroring solid upper segment; all surfaces polished; inscribed in block letters, right corner base edge of cube: "Marian Karel 1987".

Karel uses light, glass, and geometric forms to make illusionistic sculptures that challenge the viewer’s perceptions of space and dimension. He especially likes to work outdoors, where his constructions can interact with the environment, absorbing color and light. The interior of Blue Cone’s square base has a hollow space that mirrors the shape of the solid cone that sits on top of it. When light penetrates the sculpture, the hollow interior cone looks like two cones. The form that is seen is the result of refraction; the double cone does not actually exist.