Released in 1988, the Rolex reference 16520 was the brand's first and last Cosmograph Daytona model to feature an outsourced Zenith-based self-winding caliber. Discontinued in 2000, it was succeeded by the reference 116520, which introduced Rolex’s first in-house self-winding chronograph movement.

Over the years, the 16520 reference has gained a dedicated following due to its iconic status, with certain examples from various series standing out as extremely rare and highly sought after by collectors. One key factor contributing to the unique “tropical” effect seen in some dials is the varnish used by Rolex at the time—Zapon. This varnish, when applied unevenly over the silvered registers, led to distinct variations.

Notably, watches bearing S, N, T, and W serial numbers with “tropical” brown registers have captured collectors' attention. While most exhibit lighter shades of brown, a few rare pieces have surfaced featuring registers in a much darker “chocolate-like” hue due to natural ageing.

The present example is one of those rare finds, showcasing dark, intense chocolate-like tropical registers. Bearing an “S” serial, this piece from circa 1993 is offered in excellent overall condition with the original green sticker still adhered to the caseback. It further comes complete with its full set of accessories, including a guarantee stamped by a local Hong Kong retailer.