The reference 1518 is the original Patek Phillipe perpetual calendar chronograph… the inspiration for subsequent models like the references 2499, 3970, and 5970. It is truly beautiful. It is a very important wristwatch. This 1518 is in all original and unpolished condition, immaculately clean, with fat lugs and pure case lines. The condition is New Old Stock. This watch truly has no peer, in terms of condition. This is an extraordinary, museum quality watch. Original case is 18k yellow gold and is extremely clean and unpolished. Domed acrylic crystal and rectangular chronograph pushers. Dimensions are 36mm diameter, 42.5mm in length from lug tip to lug tip, and 13.9mm thick. Crystal is acrylic and case back is solid 18k gold. Original movement is the manual winding Patek Phillipe Caliber 13’’’ with 23 jewels and adjusted to 8 positions. Movement is winding smoothly and running perfectly. The pristine silver dial is 100% original and untouched, in mint+ condition. Applied golden Arabic numerals an dot markers. Railroad style minutes and seconds chapter. Day and month apertures above the “Patek Phillipe Geneve” text and moonphase and date displays above 6 o’clock. The moonphase disc is a deep blue with golden stars and moon. Hours, minutes, seconds and date hands are leaf style and golden, while the chronograph hands are blued. Strap is hand sewn black crocodile with vintage 18k Patek buckle.