The mother-of-pearl Lady-Datejust with ruby markers, and its papers.

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.

Rolex cut mother-of-pearl dials for the Lady-Datejust through the 1990s and 2000s, and no two are alike: the shell’s grain changes the colour from white to pink to grey as the light moves. Ruby markers were one of the factory options on those dials, ten stones with the date window taking the place of the marker at three. The 79173 is the two-tone Lady-Datejust of that decade, with the yellow gold fluted bezel and the two-tone Jubilee. Box and papers with a P-series serial mean this one can be dated and checked against the papers.

WGACA gives the reference as 79173, the size as 26mm, the case as steel with an 18 karat yellow gold fluted bezel and sapphire, the movement as quickset automatic, the dial as mother-of-pearl with ten ruby markers, the bracelet as two-tone Jubilee with an Oysterclasp, box and papers as included, the serial as P26xxxx, the wrist as 7.5 inches and the condition as Excellent with light scratching on the caseback. The photograph matches; the calibre, chronometer rating, reserve and 100 metres are Rolex’s published figures for the 79173.

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 papers list the ruby dial, which confirms it 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.