Strap for Datejust 31 Yellow Gold Diamond / Oyster / MOP

The Rolex Datejust 31 ref. 178158-0033 has a lug width of 16mm. This measurement is taken with a vernier calliper positioned between the inner edges of the two lugs at the point where the strap meets the case. This is a non-standard size compared to the more common 18mm or 20mm, so it is essential to verify this measurement before purchasing a compatible strap.

For an 18-carat yellow gold case, alligator straps in Mississippiensis grain — either glossy or semi-glossy — offer the most coherent aesthetic match, as the symmetrical scales complement the warmth and lustre of the precious metal. Alternatively, vegetable-tanned calf leather or shell cordovan develop a natural patina over time that harmonises beautifully with yellow gold. For a more casual approach, a technical NATO strap or vulcanised rubber band are functional and contemporary options.

Strap replacement requires a forked or pointed spring bar tool to remove the spring bars securing the strap to the lugs. It is advisable to work on a soft surface to protect the yellow gold case from scratches. Given the value of this timepiece, entrusting the operation to a watchmaker or the Casati Milano atelier — where fitting is verified to the millimetre — is strongly recommended.

Yes. High-quality artisanal aftermarket straps made specifically for the 16mm lug width are fully compatible with this reference, provided they are manufactured to correct millimetric tolerances. Casati Milano produces straps in 16mm width using alligator, calf leather, shell cordovan and other premium materials, with fitting tested directly on Rolex cases and an 18-month production defect warranty.

The lifespan of a leather strap depends on the material, tanning quality and conditions of use. A high-grade alligator or shell cordovan strap, used carefully and rotated regularly with other straps, can last between three and seven years while maintaining good structural integrity. Perspiration and humidity are the primary causes of deterioration: avoiding prolonged use in hot, humid conditions significantly extends the strap's life. Casati Milano backs its straps with an 18-month warranty against manufacturing defects.