Strap for Day-Date 36 Yellow Gold / Strap / Silver Diamonds

The lug width of the Rolex Day-Date 36 reference 118138-0135 is 20 millimetres. This measurement refers to the internal distance between the threaded lugs on the watch case where the strap attaches. It is critical to verify this dimension before purchasing an aftermarket strap, as even a 1 mm discrepancy (19 or 21 mm) compromises both the fit and aesthetic integration of the watch.

For a yellow gold Day-Date 36, natural alligator (brown or black), vegetable-tanned calf leather, or shell cordovan are the recommended options. Alligator offers maximum aesthetic contrast and the most predictable patina development; vegetable-tanned calf ages nobly with amber tones; cordovan is the choice for collectors seeking a crystalline texture that dialogues with the luminosity of gold. NATO fabric straps are not advised for daily wear on this formal model.

Strap replacement requires a specific tool: a spring bar tool with a bifurcated tip. Position the tip in the transverse hole of the lug, compress the internal spring gently, and slide the strap out of the terminal. Proceed carefully: yellow gold is malleable and scratches easily. It is advisable to entrust this operation to a certified watchmaker or the Casati Milano atelier service, where the work is performed under optical magnification with a guarantee against damage.

Yes, provided the strap is manufactured with lugs measuring exactly 20 mm. Artisanal straps in alligator, calf, or shell cordovan from reputable manufacturers are fully compatible. It is essential to select producers who explicitly declare lug width and tanning quality. Casati Milano offers bespoke straps for the Day-Date 36, with direct consultation and an 18-month warranty on manufacturing defects.

Durability depends on material and usage patterns. Natural alligator typically endures 3-5 years of daily wear, with positive aesthetic ageing (patina development). Vegetable-tanned calf ages more rapidly but nobly (2-4 years of intensive use), developing an amber cognac patina. Shell cordovan is more durable (4-7 years) due to fibre density. Minimal maintenance—avoiding humid environments, protecting from perspiration and water—significantly extends the strap's lifespan. Casati Milano provides personalised guidance on strap care.