Okay, I admit, these aren’t the most elegant labels when discussing luxury replica watches. But, if you spend enough time with the Panerai people, you’re bound to hear the terms “sausage” and “sandwich” used when discussing Panerai watches and their dials. So, what exactly are Panerai’s sandwich and sausage dials? These names specifically refer to how the luminescent material is applied to the dial of a Panerai watch. Sandwich dials have recessed luminescence, while sausage dials include luminescent paint that curves over the top of the dial. 
Panerai watches are some of the most recognizable watches on the market, featuring unique cushion-shaped cases and sharp dials. Take a look at the entire Panerai collection. You will quickly notice that most dials are dark in color and feature sticks and oversized Arabic numeral hour markers. The dials are usually executed simply, with a pair of hands in the center, sometimes accompanied by a running subdial and occasionally a date window.
It is often said that all Panerai watches look almost the same, and it is hard to tell the difference between one model and another. However, upon closer inspection, it is clear that the differences lie in small but important details – like the sandwich dial versus the sausage dial.
Panerai’s origins are far removed from the luxury Swiss watch brand we know today – it was founded by Giovanni Panerai as a watch store and workshop in Florence, Italy, in 1860. In the early 20th century, the founder’s grandson, Guido Panerai, transformed the family business into a supplier of precision instruments to the Italian Royal Navy or Regia Marina. in 1916, Panerai patented “Radiomir,” a self-luminous radium-based coating that would make the dials of the company’s military instruments more luminous for the Italian Navy.
Using Rolex-supplied timepieces powered by Cortebert pocket watch movements, Panerai developed dive watches for the combat divers of the Italian Navy’s secret underwater program. These watches became what we know today as the Panerai Radiomir models, featuring significant cushion-shaped cases, wire lugs, highly luminous dials, oversized crowns, and extra-long straps. These replica watches were constantly modified and upgraded to meet the exacting needs of combat divers.
For example, Giuseppe Panerai (son of Guido) changed the structure of the dial to have overlapping discs. The top dial is made of anodized aluminum. It features cutouts for the hour markers – four Arabic numerals and eight sticks – to allow illumination by the radium paste applied to the chassis. Thus was born Panerai’s sandwich dial.
Given how important readability in the dark was to the military, Panerai focused on luminous materials for its watch dials. By the late 1940s, the company registered the more neutral-sounding name “Luminor” and moved away from “Radiomir” due to growing public fears of radium and radioactivity. In the mid-1960s, Panerai replaced all radium-based luminescence with tritium-based luminescence – just like the rest of the copy watch industry. Self-luminous tritium is still radioactive but significantly safer than radium.
These days, Panerai uses modern (and non-reactive) Swiss Superluminova on their dials. Radiomir and Luminor are no longer used as luminous names but now as the names of the two most important Panerai watch models in the brand’s current catalog.