The blue dial is degraded and has greenish tones that are the result of a change over the years
This reference 18138 specifically indicates this configuration with diamonds on the bezel and lugs and Rolex plaque
Since its first appearance in Basel in 1956, the Rolex Day-Date has always been automatic, water and shock resistant, with indications not only of hours, minutes and seconds, but also of day and date.
The present 1985 model is embellished with a diamond vignette dial. The bezel and lugs feature brilliant-cut diamonds, but the bezel features a Rolex plaque near 6 o'clock, which is not often seen and which increases the rarity of this piece.