Gold-capped describes a steel watch case with a layer of gold fused onto its front using heat and pressure. Of the gold coatings used on watch cases, capping is the thickest. Only the top of the case is gold. The steel underneath still shows in places, which helps you tell it apart from solid gold.
How is a gold-capped case made?
A gold cap starts with a steel case. A layer of gold is fused onto the front of it using heat and pressure. Rolex, which called its versions gold shell, formed a sheet of 14K gold under pressure, hammered it, and soldered it onto a stainless steel case. The result is a fairly thick layer of gold over steel. The gold covers only the top of the case.
How can you tell a gold shell Rolex from solid gold?
Start with the rehaut, the ring around the edge of the dial. On a gold shell case it is bare steel. On a solid gold case it is gold. Then turn the watch over. On a gold-capped case, the undersides of the lugs show bare steel. The bracelet is another clue. Rolex apparently never made a gold shell bracelet, so these watches came with electroplated bracelets instead.
Not to be confused with
Gold-filled cases also carry a layer of gold, but a thinner one. It measures about 80 microns, or 0.08 mm. A gold cap is thicker, at roughly 200 microns, or 0.2 mm. Nor is a gold-capped case solid gold. Underneath the cap is steel. Turn the watch over and the undersides of the lugs show bare steel. On a Rolex gold shell case, the rehaut is bare steel too.
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