Signed Rolex, Oyster Perpetual, Cosmograph, Daytona, Ref. 116519, Case No. K'194'414, Circa 2004

Underline dials are a very rare and their origins are somewhat of a mystery. The first appearance of the underline is in the early 1960s on a number of Rolex models, not only the Daytona. It is accepted that that underline indicates the presence of tritium rather than radium on the dial, and it is considered one of the most appealing feature to have on a Rolex timepiece. The reason for its presence is still debated. Obviously, at this point in time it has no links whatsoever with radium or tritium: both compounds having been superseded by Luminova in 1998. The most probable explanation for it is that it is the result of a batch of dials with a printing mistake which eluded Rolex quality controls and surfaced to the market. Alternatively it has been hypothesized that the line served as an alignment guide for the lines of text, or that it might be an aesthetic detail tested on very few dials. While the origin of this dial might be shrouded in mystery, on the contrary the rarity, appeal and collectability it grants to this timepiece are clear without the trace of a doubt.