Understanding Vickers Hardness in Watch Steel

The Vickers hardness test was developed in 1921 by Robert L. Smith and George E. Sandland at Vickers Ltd. It measures a material's resistance to plastic deformation by pressing a diamond pyramid indenter into the surface under a controlled load, then measuring the size of the indentation left behind. The smaller the indentation for a given load, the harder the material.

The result is expressed as a Vickers Hardness number followed by HV: a material rated 200 HV is harder than one rated 150 HV. Higher numbers mean greater resistance to scratching, denting, and surface wear. The Vickers scale is one of the most widely used hardness measures because it works across the full range of metals and produces consistent, comparable results.

In watchmaking, the Vickers test is the standard method for specifying case steel hardness. It is the number behind claims like "800HV hardened steel" and determines how a watch case holds its finish under the contact points of daily wear.

Standard 316L stainless steel rates at approximately 200 HV. This is the steel used in the majority of watches at every price point, from fashion brands to most Swiss manufacturers. At 200 HV, the steel scratches from contact with keys, coins, desk surfaces, and belt buckles. After one to two years of daily wear, the case edges and flat surfaces accumulate a visible network of fine scratches. The watch looks worn.

800HV hardened surgical steel is four times harder than standard 316L on the Vickers scale. The hardening process applies controlled thermal and mechanical treatment to the steel, rearranging its crystalline structure to resist deformation. At 800 HV, the steel resists scratching from the everyday objects that would mark standard steel. The case edges and surfaces hold their finish significantly longer under daily contact.

The practical difference is visible after 12 to 18 months of daily wear. A 200 HV steel case shows accumulated scratches on the flat surfaces and case edges. An 800 HV case in the same conditions holds its finish with only minor surface marks at the highest contact points such as the caseback and clasp.

Söner applies 800HV hardened surgical steel specifically to the Nostalgia and Amorous collections. These are the dress watch collections where maintaining a polished finish under daily office and formal wear conditions matters most. The Legacy and Momentum collections use standard 316L steel, which is appropriate for their larger case size and active wear context. For the full technical explanation of steel grades in rectangular cases, see our guide to watch case steel materials.

The most vulnerable points on any watch case are the edges: the transitions between flat surfaces, the lug ends, and the caseback perimeter. These points contact hard surfaces most frequently when the wrist rests on a desk, when the watch is set down, or when it contacts a belt or cufflink.

On a rectangular case, these edges are more defined and more exposed than on a round case. A round case has no sharp corners. A rectangular case has four of them, plus four long straight edges where the top and side surfaces meet. Under contact with hard objects, these edges are the first to show wear on a lower-hardness steel.

At 800 HV, these edges hold their definition significantly longer. The geometric precision of a rectangular case, which is part of its visual authority, is preserved by the steel hardness that resists the contact points most likely to blur that precision. This is the specific reason Söner chose 800HV hardened steel for the Nostalgia and Amorous rather than standard 316L.

Vickers hardness (HV) and Mohs hardness are two different scales that measure hardness in different ways and are not directly comparable.

The Mohs scale is a relative ordinal scale from 1 (talc) to 10 (diamond). It tells you which material scratches which: a material at Mohs 7 will scratch any material at Mohs 6 or below. Sapphire crystal rates at Mohs 9. Standard steel rates at approximately Mohs 5 to 6. This is why sapphire crystal is not scratched by steel keys or coins in everyday use.

The Vickers scale is a quantitative measure of indentation resistance with specific numerical values. It is used for precise engineering specifications where a relative ranking is not sufficient. 200 HV vs 800 HV tells you exactly how much harder one steel is than another. The Mohs scale cannot make that distinction within the steel category because both standard and hardened steel fall within the same Mohs range.

For watch buyers: Mohs hardness is the relevant scale for comparing crystal materials (sapphire vs mineral glass). Vickers hardness is the relevant scale for comparing steel case grades.