In the 18xx Day-Date series the last digit is the bezel and nothing else: 1802 smooth, 1803 fluted, 1804 gem-set, 1806 Florentine, 1807 bark. So the reference alone tells you the bezel before you have seen the watch, and two Day-Dates that look nothing alike can be one digit apart.
Reference record
Production
1959–1977
Model
Day-Date (Gem-Set Bezel)
Case material
18k Gold / Platinum
Case size
36mm
Movement
Automatic
Calibre
Cal. 1555 / 1556
Dial colours
Silver / White, Black, Brown / Champagne
Market value band
$22k – $50k
Notable
—1804 is the factory gem-set bezel. Stones added afterwards do not make a watch a 1804.
What the specification implies
—The trailing digit of an 18xx Day-Date encodes the bezel it left the factory with.
Common questions
When was the Rolex 1804 produced?
The 1804 was produced from 1959 to 1977.
What movement does the Rolex 1804 use?
The Rolex 1804 runs the Cal. 1555 / 1556, an automatic movement.
How do I check a Rolex 1804 with Watch Safe?
Look up the watch's serial number in the Watch Safe registry to see whether a record exists or a theft flag is attached. A registry search identifies records for a specific serial; it does not authenticate the watch. Authentication is performed in person by an independent expert authenticator, and Watch Safe records and publishes the result.