"Diminished Inversion (It's all in the concave)" is a parlor kaleidoscope by Robert Cook and Jocelyn Teh of Arcana Kaleidoscopes. This is a brass, copper and steel construction with a barrel 210x65mm. It has antique patination with polished highlights. There are two different mirror systems, a 2-mirror and a 3-mirror and two 5-1/2" in diameter object wheels, one with agates and one with stained glass. An assemblage is secreted under the Fiddle-back Tasmanian Oak base. This scope measures 11-1/2"T x 11"L x 6-1/2"W at the base and it is signed (Robert Cook), dated (2018), numbered (7373) and marked "Arcana" by the artist.