In production from approximately 1995 to 2005, reference 3990 is virtually identical to the celebrated reference 3970E, with the addition of a diamond-set bezel and matching luxurious dial. The model is Patek Philippe's first perpetual calendar chronograph wristwatch to feature a diamond-set bezel, setting the design codes for its successor reference 5971. Reference 3990 was cased in yellow gold, pink gold, white gold, and more exclusively, in platinum. Like its sibling reference 3970, it was fitted with a Lemania-based movement.

The reference hardly ever appears on the market, having been produced in exceedingly low numbers. According to research, the present watch is previously unknown to the auction market, and the fifth example cased in platinum to appear in the public eye.

The present example, cased in platinum, features diamond-set numerals and a baguette diamond bezel, totaling 2.77 carats in total. The semi-glossy dial is black, and contrasts wonderfully against the diamond markers and lustrous white tones of the platinum case. Luminous hands furthermore give the watch an incredibly modern appearance that collectors and scholars love - a feature that is often requested, but not necessarily granted, on modern Patek Philippe special order watches today.

Most stunning is the overall condition of the watch. Featuring sharp case proportions, crisp hallmarks, and incredible "fluting" to the lugs, the watch is preserved in near pristine condition. It is furthermore enhanced by its Certificate of Origin, additional platinum numbered case back, setting pin, product literature, leather wallet and fitted presentation box, making for a very complete and original set.