In Part I of this series, we shared some suggestions on how best to remove a damaged watch crystal from your watch case. Now that the old crystal is out, let’s talk about what kind of new crystal you want to attach to your timepiece and exactly how to get it snugly into the case where it belongs.
You are not locked into replacing your watch crystal with one exactly like the one you just removed. There are plenty of options out there if you want to upgrade to a higher-quality glass or change the dome shape. Many crystals come in standardized sizes that meet manufacturer specifications or can be customized to the size of your watch.
The three primary materials used to make watch crystals are acrylic, mineral, and synthetic sapphire, and they all differ considerably as to scratch resistance, durability, and affordability.
Your cheapest option is acrylic. It’s a transparent thermoplastic material better known as plexiglass, and you see it used in kids’, vintage, and less-expensive watches. For example, you might be surprised to learn that most Rolex watches in the ‘70s and ‘80s were made with acrylic crystals. That’s because it’s rigid, easy to replace, and one of the clearest plastics on the market.
And because acrylic is cheap, it has some distinct advantages over your higher-end watch crystals. Acrylic is an excellent option if you live an active lifestyle, dive, or even if you tend to bump into stuff a lot. Of all the types of watch crystals out there, acrylic is most likely to scratch, but least likely to shatter. Scratches you can buff out and cracked acrylic crystals are inexpensively replaced since these types of bumps and bruises generally don’t compromise the integrity of the watch.
However, if your glass shatters, which is more likely with a mineral or synthetic sapphire crystal, you’re going to need to take it to an authorized professional watch repair shop. Shattering exposes your movement to outside factors like water, for example, if you happen to be in the middle of a swim or dive. A shattered crystal also produces tiny shards of glass, which could severely damage your watch if they get into the movement.
Much like the glass in your home windows, a mineral crystal is clear, tempered glass. It has a hardness rating of 5 on a Mohs scale, which means it is highly resistant to scratches. The Mohs scale measures material hardness on a scale of one to 10, with 10 being the hardest. The lower the rating, the more easily you can scratch the material’s surface. Acrylic has a Mohs rating of three to four which explains why it is more prone to scratches and other surface blemishes.
You will usually find mineral crystals, or mineral-sapphire blends, on mid-range watches. A mineral crystal has significantly higher scratch resistance than acrylic, but not nearly to the level of synthetic sapphire. However, mineral crystals are more shatter-resistant than sapphire.
In the race to increase scratch and shatter protection without the high price tag of straight synthetic sapphire, a few companies have developed proprietary crystals, including Seiko’s Hardlex and Invicta’s FlameFusion. Seiko created Hardlex as an affordable option to fill the gap between acrylic and synthetic sapphire. It is durable and more scratch-resistant than mineral glass, and more shatter-resistant than sapphire. Invicta’s FlameFusion is precisely what the name implies – a high-temperature fusion of mineral and sapphire crystals, creating an extraordinarily shatter-resistant glass almost as scratch-resistant as synthetic sapphire.
Finally, the synthetic sapphire watch crystal, referred to as the Holy Grail of watch crystals, is nearly impossible to scratch. Sapphire has a Mohs hardness rating of 9, second only to that of a diamond. You’ll find this type of crystal on watches made by luxury giants like Rolex and Patek Philippe, as well as on higher-end Citizen, Movado, and Tissot watches, just to name a few.
If your old crystal was glued in, you’ll need to install the new crystal in much the same way by applying GS crystal cement, two-part epoxy, or UV glue to the inside edge of the bezel and fitting the glass into place. Everyone seems to have their preference for which glue they like to use, so you can ask a watch repair pro if you’re unsure.
However, one absolute thing is to make sure the inside of the watch bezel, or part of the case where the crystal will sit, is entirely gunk-free. We suggested in the previous article that a screwdriver is a great tool to scrape away glue residue. If the debris is incredibly stubborn, try applying some acetone, but don’t let the chemical touch your new crystal.
Once you have a super-smooth surface, it’s time to apply the glue. Your first step is to test out how fast the glue flows through the applicator by using it on a small notepad or other temporary surface. Like super-glue, you don’t need a lot, and if it comes out too fast, you might end up with a big, gluey mess all over your watch case and new crystal.
The next step is to apply the glue according to the manufacturer’s instructions and place the new crystal so it fits right on the inner edge of the bezel. For UV glue and two-part epoxy, you’ll want to use your polishing cloth to remove any excess adhesive immediately after placing the crystal. When using crystal cement, allow it to harden and seal the crystal in place before taking a toothpick or peg to scrape away any excess around the edge. Be careful not to scratch your new crystal.
Remember the tools we introduced in Part I? We’re referring specifically to the watch crystal press and the crystal lift. For reattaching compression fit crystals, the crystal lift will be your best option. To replace crystals with gaskets or tension rings, or rotating bezels, use a crystal watch press.
If you get stuck anywhere in this process, we advise you to reach out to a watch repair professional. Whether it be a repair for a Seiko, Accutron, Bulova, Timex, or Kate Spade, we have seen it all. We’re a safe, convenient, and affordable option if you decide you want to drop off or mail in your broken watch.