The A. Lange and Sohne Datograph Lumen Up Down in platinum, reference 405.034, was introduced in 2018 as a strictly limited edition of just 200 pieces. Its 41 mm platinum case, measuring approximately 13.4 mm thick, houses the hand‑wound calibre L951.7, offering a robust 60‑hour power reserve and the revered fly‑back chronograph mechanism. The semi‑transparent smoked sapphire “Lumen” dial, crafted from German silver and sapphire segments, delivers a mesmerizing interplay of light and luminescence: the oversized date, power reserve, sub‑dials, tachymeter scale, and hands all glow vividly in darkness, while revealing the movement beneath in daylight. This model elevates the Datograph Up/Down lineage with both technical refinement and theatrical visibility, making it a standout for seasoned collectors. The exhibition caseback showcases the haute‑horlogerie finishing—German silver bridges, hand‑engraved balance cock, gold chatons, and blued screws—underscoring its artisanal pedigree. As the fourth installment in Lange’s Lumen series, this piece embodies both innovation and exclusivity, marrying traditional chronograph architecture with avant‑garde dial treatment. Like New with A. Lange and Sohne box and papers dated 2019.