Inauthentic Cartier 'Must de Cartier' Moonphase Watch Prototype

This is a circular wristwatch bearing the 'must de Cartier' logo, featuring a moonphase complication at the 12 o'clock position and a date window at 6 o'clock. The watch presents significant red flags regarding authenticity. The dial displays thin, printed Roman numerals and a 'Japan Movt' marking at the base, which is inconsistent with genuine high-end Cartier timepieces that utilize Swiss movements and typically feature 'Swiss Made' or 'Paris' designations. The case appears to be made of a basemetal with failing silver-tone or gold-tone plating, showing heavy wear, pitting, and oxidation across the bezel and lugs. The gold-tone hands and crown show discoloration. The black leather strap is in poor condition with visible cracking and surface loss. The overall craftsmanship, specifically the alignment of the date window and the quality of the dial printing, suggests this is a low-quality counterfeit rather than a genuine vintage Must de Cartier Trinity or Colisée model.