David C. from Taiwan asks:
What is the difference between gold-plated and PVD gold? Especially when it comes to watch cases. Which one is better? Which one lasts longer?
One thing that is important to state, is that not all PVD or plating processes are the same. Meaning, that there are really great platings and really bad PVD processes... and vice-versa. PVD is really a process more than a material. It stands for "physical vapor deposition" and is a rather effective way of literally blasting metal with another metal to bond them. Modern PVD processes are quite good, but really depend upon the material that is being blasted, and other details. A decent lab with the right equipment produces extremely good PVD-coated metal.
So, PVD is a coating, while plating is... well, a plating. Gold-plated metal is usually steel with real gold plated over it. A layer of gold, measured in microns (the thickness varies of course) is plated to metal to offer the look of gold at a lower cost. Gold-plating is more rare in watches these days because PVD gold has some advantages, but not all of them. A good gold-plated case can actually appear to look more like solid gold that many PVD coatings. Why? Well because it is really gold. The weakness is that overtime lots of rubbing can wear gold plating down, or scratches can reveal the base material.
For longevity, people often prefer PVD coatings. They are more expensive to apply, and are more durable over time. Though often times you'll notice that PVD gold cases are "PVD gold tone." That means no gold is actually used. Because PVD is a process versus a material, we believe that you can use gold in the coating, or just materials that look like gold. We've included an image that helps describe what a quality PVD gold coating consists of. You can see that in this high-end application there is steel, then a layer of titanium nitride for durability, and on top of that is a thin layer of 23.5 carat gold. That is a really good application, but some PVD coatings have merely gold-colored materials that are bonded to steel.
Overall, PVD coatings are going to be more durable in the long run when it comes to modern high-end watches. Though, in some cases, a gold-plated case can look better depending upon the materials used. It is difficult to answer which is better because is can really depend on the specific coating, cost of the process, and skill of the lab.
We choose a few questions each week and publish them. Want to ask the aBlogtoWatch team a question? We want to hear from you »