18K Yellow Gold vs. Everose Rose Gold vs. Grey White Gold: Horological Alloy Composition & Vickers Hardness

Why Does 18K Everose Gold Never Lose Its Warm Pink Hue?

Traditional 18K pink and red gold alloys derive their warm coloration from a 19% to 21% copper (Cu) fraction; however, when exposed to marine saltwater, chlorine, or ultraviolet radiation over decades, surface copper atoms can leach out, shifting ordinary rose gold toward a pale yellow tone. To eliminate this phenomenon permanently, horological 18K Everose gold alloys 75.0% pure gold with approximately 20.75% oxygen-free copper, 2.2% silver, and 2.0% pure platinum (Pt).

Platinum forms a noble intermetallic lattice bond with copper inside the solid solution, increasing the electrochemical corrosion potential of the alloy. When inspected under our Fischer XRF spectrometer at Place Vendome, this 2.0% platinum signature immediately distinguishes authentic horological Everose cases from ordinary jewelry-grade 18K rose gold.

Why Does White Gold Weigh Slightly More Than Yellow Gold in the Same Watch?

Collectors comparing a solid 18K White Gold Rolex Daytona Ref. 116509 (221.4g) against a solid 18K Yellow Gold Daytona Ref. 116508 (216.5g) frequently notice a 4.5-gram to 5.0-gram mass premium on the white gold reference. This difference stems directly from atomic density: whereas 18K yellow gold uses equal parts silver (10.49 g/cm3) and copper (8.96 g/cm3) for its remaining 25% alloy balance, horological 18K white gold replaces most of that silver and copper with 13% to 15% pure palladium (Pd, density 12.02 g/cm3) and trace platinum.

Because palladium is significantly denser than copper and silver—and bleaches the natural yellow colour of Au750 throughout the entire thickness of the billet—solid 18K palladium white gold achieves a higher specific gravity (15.95 g/cm3 vs. 15.58 g/cm3) and never requires superficial rhodium plating that could flake during case refinishing.

How Does Cold Forging Increase the Scratch Resistance of 18K Gold Cases?

Pure 24-karat gold (Au999) has a Vickers hardness of only 25 to 30 HV, making it far too soft for a water-resistant mechanical wristwatch case or integrated bracelet. By alloying 75.0% pure gold with copper, silver, palladium, and platinum, the baseline cast hardness rises to roughly 140 HV. Before any middle case, bezel, or bracelet link is milled for our Place Vendome vitrines, the vacuum-cast Au750 billet undergoes multi-stage hydraulic cold-forging and controlled age-hardening heat treatment.

This mechanical deformation compresses the crystalline grain boundaries and induces precipitation hardening across the gold-copper superlattice, elevating final surface hardness to 190–215 HV—comparable to Austenitic 316L stainless steel—while preserving the unmistakable thermal conductivity and 210+ gram wrist presence of solid 18-karat bullion.