The two-tone Lady-Datejust with the blue diamond dial.

The Lady-Datejust is the Datejust at 26mm, the size Rolex made for women from the 1950s until it moved the line to 28mm in 2015. It is the same watch in miniature: an Oyster case with a screw-down crown, an automatic chronometer movement, the date under its Cyclops lens at three, a fluted or engine-turned bezel, and a Jubilee or Oyster bracelet. Because Rolex made them for six decades in every dial and metal, the pre-owned market is deep and this is where the money goes when people search for a women’s Rolex.

The blue sunray dial with factory diamond markers was one of Rolex’s catalogue options on the 179173, the 2000s two-tone Lady-Datejust with a yellow gold fluted bezel and a Jubilee with the Crownclasp. Blue against yellow gold is a stronger look than champagne, and the ten diamonds pick up the bezel. WGACA’s 28mm is the size Rolex moved the line to in 2015; the 179173 reference is the 26mm watch.

WGACA gives the reference as 179173, the dial as blue with diamonds, the clasp as a hidden crown clasp and the condition as Excellent with light scratching and tarnishing throughout. It does not state box, papers or year, and its 28mm conflicts with the reference. The fluted bezel, diamond markers and Jubilee are from the photograph; the calibre, chronometer rating, reserve and 100 metres are Rolex’s published figures for the 179173.

WGACA authenticates in-house and is not a Rolex authorised dealer, and Amazon adds its 30-day return window. Ask for the serial, whether box or papers come with it, and when it was last serviced. Nothing here was measured on the watch. Ask whether the diamond dial is factory.

This unit is sold by What Goes Around Comes Around (WGACA) through Amazon Luxury Stores, authenticated by the seller with Amazon’s 30-day return window on top; it is one piece, and when it sells the listing goes away, so the second button opens the live search for 26mm Lady-Datejusts.

Steel and two-tone Lady-Datejusts have resold close to what pre-owned buyers paid, sometimes more, sometimes less; that is a pattern, not a promise, and nothing here is investment advice.