Brand: Gruen

Model: Precision Day-Nite "Jump" Dial ref. 510 Rss CA; Swiss Made circa 1960s

Case: 10 microns yellow gold-plated case with stainless steel screw-down caseback is approximately 33mm excluding the original unsigned winding crown

Strap: Vintage new old stock (NOS) 18mm brown leather strap with matching yellow gold-tone tang buckle

Movement: Gruen cal. N510CA manual-winding movement (17 jewels) with original dust cover; specially modified for day-night "jumping" function; Swiss Made

Features: Stunning original silver "sunburst" day and night "jump" dial with gold-tone hour markers; day-night feature where hour markers flip underneath the dial from black during daytime hours (6 AM - 6 PM) to fluorescent Radium "nite-glo" green during nighttime hours (6 PM - 6 AM); original Radium hands; original center sweeping-seconds hand; attractive 33mm gold-tone case with matching original gold-tone handset

Condition: Nearly new old stock (NOS) original condition overall with only the lightest signs of wear consistent with storage and handling; razor-sharp case is completely unpolished with all of the original finishes in tact; light wear to the gold plating on the original crown from winding; crisp stainless steel screw-down caseback with defined engravings; gorgeous original "Day & Nite" dial; nice original Radium hands; a few minor superficial scratches on the domed acrylic crystal

Other: Looking for a unique conversation piece? Look no further than this incredible Gruen Precision Day-Nite. All Day-Nite models are rare, but try finding one in this condition. This particular example appears to have been worn only a handful of times and is in mint condition overall. It slides nicely under the cuff of a dress shirt, but can also be worn effortlessly with a t-shirt and jeans - Show off those fluorescent green hour markers!