Strap for Datejust 31 Yellow Gold Fluted / Oyster / Silver Diamond

The Rolex Datejust 31 reference 178278-0037 has a lug width of 16mm. This measurement is taken internally between the two case lugs at the point where the strap attaches. Always verify this figure before purchasing any aftermarket or replacement strap.

For an 18-carat yellow gold case measuring 31mm, the most suitable materials are vegetable-tanned alligator and shell cordovan, both in smooth or semi-polished finish. The regular grain of alligator complements the lustre of the gold, while cordovan develops a patina over time that harmonises with the warm tones of the metal. Lacquered box-calf leather is a modern and versatile alternative.

To replace the strap on a Rolex Datejust 31, you will need a spring bar tool with a double tip, ideally with a nylon or PTFE protective tip to avoid scratching the yellow gold lugs. Insert the tool into the lug hole, compress the spring bar and slide it out. The operation takes approximately five minutes and does not require a visit to an authorised service centre. If in doubt, consult a watchmaker or the Casati Milano atelier.

Yes. Any strap with a 16mm attachment is technically compatible with the Rolex Datejust 31 178278-0037. Milano Straps and Casati Milano produce handcrafted straps to this exact width, with finishes suited to a yellow gold case — from fine leather to silk NATO and deployant clasp versions in gold. The quality of materials and craftsmanship determines the longevity and aesthetic result.

The lifespan of a leather strap depends on the material, care and frequency of use. A handcrafted vegetable-tanned alligator strap typically lasts between two and four years with daily wear, and longer with periodic conditioning using a quality leather cream. Shell cordovan tends to be more durable due to the density of its fibre structure. Casati Milano straps carry an 18-month guarantee against manufacturing defects.