A fake IWC platinum watch has a stainless steel case. IWC builds genuine platinum models from 950 platinum, an alloy with 95 percent platinum. Platinum density is 21.45 g/cm3. Type 316L stainless steel density is 7.98 g/cm3. A platinum case weighs about 2.7 times as much as the same case in steel. Replica cases are steel with plating or a stamp.

What "platinum" means in a replica listing

Sellers use the word for three products: a rhodium plated steel case, a platinum color PVD coating, or a steel case stamped PT950. Each one has a steel core. Rhodium plating on replica cases runs 0.5 to 2 microns thick. It wears at the crown, the lug tips, and the clasp within months of daily wear.

Weight and density

Platinum: 21.45 g/cm3. 18k white gold: 15.5 to 16.5 g/cm3. 316L steel: 7.98 g/cm3. 904L steel: 8.03 g/cm3. Weigh the watch on a digital scale and compare it with the steel version of the same reference. A 42 mm platinum case adds tens of grams. That gap sits outside normal production tolerance.

Hallmarks

Swiss law requires an official hallmark on precious metal watch cases. Platinum cases carry a Pt950 stamp and an assay office mark. Replica factories laser etch "PT950" or "950 Plat" on steel. Under a 10x loupe, laser marks look flat and shallow. Struck hallmarks have depth and a raised rim. A stamp alone is not proof of material.

Plating wear

Solid platinum keeps the same gray white color at every point. Rhodium plating changes color at contact points. Inspect the crown, the case back threads, the lug holes, and the clasp edge. Platinum forms a dull gray surface layer over years. Plated cases stay bright until the coating fails, then show the base metal.

Price floor

Platinum spot trades near $1,000 per troy ounce, or about $32 per gram. A 60 gram case blank costs about $1,900 in raw metal. Machining waste adds 10 to 20 percent. A $300 to $600 replica cannot hold a solid platinum case. Genuine IWC platinum references list above $50,000.

Tests that fail

Magnet test: platinum is paramagnetic. 316L and 904L steel are austenitic and nonmagnetic. Both metals react the same way to a magnet. Warmth test: platinum thermal conductivity is 71.6 W/m-K. 316L is about 16 W/m-K. Both feel cool at room temperature. Skin heat and room temperature change the result.

Tests that work

• XRF: an X-ray fluorescence gun reads alloy composition in seconds. Jewelers, pawn shops, and assay offices use handheld units.
• Density check: divide case mass by case volume. A result near 21.45 g/cm3 points to platinum. Movement, crystal, and gaskets skew the number.
• Assay office: an official test gives a legal hallmark.

Reference check

IWC lists the case material for each reference. Compare the reference number on the case back with the IWC catalog. A steel reference does not exist in platinum, and a platinum reference does not exist in steel. Replica reference numbers often match no catalog entry.

Legal note

Selling a steel watch as platinum is fraud. The FTC Jewelry Guides require accurate precious metal labels in the US. Customs can seize counterfeit watches under 19 USC 1526. Trafficking in counterfeit goods carries penalties under 18 USC 2320.