Pocket Watch Crystal Replacement: Selecting the Best Option

Published: June 19, 2014

We receive a lot of inquiries about pocket watch crystals. Some pocket watch owners such as civil war reenactors are interested in the safest type of crystal. Other pocket watch owners are interested in only the most “authentic” crystal replacements – including some civil war reenactors.

There are two basic replacement options for pocket watches: glass (mineral glass) or plastic (acrylic). I don’t know of anyone cutting sapphire crystals for pocket watches, as the cost would be tremendous for such large, thick sapphire.

Glass Pocket Watch Crystals Explained

South Bend Pocket Watch With Broken

IMAGE ONE – This open face South Bend pocket watch had an original style glass crystal that was approximately 4mm thick. Breaking it was hard – it knocked the second hand and minute hands off and destroyed the watch’s balance staff.

There are two types of crystals available for Pocket Watches. Very thin glass crystals for pocket watches in hunting cases, and thicker crystals for open face pocket watches.

Glass crystals for hunting case watches are hard to find today (especially in the most desirable sizes), as the only glass options are old stock crystals. In most cases these are over 100 years old. Very old stock! Often, the stickers showing size have been on these crystals for so long that they leave a mark when they’re removed. If the crystal isn’t very rare, a watchmaker might be bold enough to polish the mark off. Most leave the mark in place and instruct the customer to be thankful they still had one left in the size needed.

Hunting case crystals are in very high demand today because of poor supply and because they are exceptionally easy to break. Hunting case crystals have been described as “parchment thin.” That is a clear exaggeration, but it drives the point home. Factor in that older glass simply doesn’t have the strength of new glass formulations, and you’ll understand why some of my customers have broken hunting case crystals when they’ve done simple things like pull the crown out to set the time.

Open face glass pocket watch crystals break less often because they are much, much thicker. Percentage wise, I don’t get in many open faced watches with glass crystals. Pocket watches with lots of service marks in the back case almost never have glass crystals, because back in the 20’s, or 30’s, or 60’s, or any other time in the last hundred years, a watchmaker has substituted the glass crystal for a plastic crystal.

Interestingly enough, at least 70% of the open face pocket watches we receive that have glass crystals are pre-1890. I believe this is because owners stopped having these watches serviced as thinner, smaller pocket watches came out. Had they continued to use the watches, and service them, normal crystal changes would have migrated them to plastic.

Open face pocket watches common have gouges in their dials. I attribute this to damage done by the thick glass crystals when they were broken during normal use. T

Plastic Pocket Watch Crystals Explained

Pocket Watch Crystal Packaging

The top package was made 07/1945. The below package is from the 50’s and guarantees to not “discolor.”

From left to right:  Postwar Pocket watch crystal from 1950s (no yellowing), Wartime Pocket Watch crystal (yellowed), Prewar crystal (green), [bottom row] New Pocket Watch Crystal produced 2013.

From left to right: Postwar Pocket watch crystal from 1950s (no yellowing), Wartime Pocket Watch crystal (yellowed), Prewar crystal (green), [bottom row] New Pocket Watch Crystal produced 2013.

I have seen claims that Germanow Simon (GS) began manufacturing plastic crystals in 1916. However, their website says they began doing so in early 1920’s. The best explanation for this that I have heard is that the company changed its ownership and legal structure, breaking continuity.

Regardless, the earliest plastic crystals made by GS were made of cellulose. By the 1930’s, they were moving to acrylic, which we still use in plastic crystals today.

For the pocket watch owner who intends to carry their watch, plastic is the best option. Plastic will break, but it won’t shatter and stab you in the leg. It won’t shard and damage the watch. And when you have your watch serviced, all but the deepest scratches can be buffed out of the crystal, leaving it looking like new.

Some older formulations of plastic crystals yellow and release gas very slowly – nitrogen dioxide and nitric acid. This gas is trapped between the dial and the crystal, and can corrode the hands. Plastic crystals made by GS from the 1950’s or later will not yellow, and they won’t release these gases.

There are plastic pocket watch crystals available – we stock around 1,000 in various sizes and with various heights. Fitting a hunting case crystal is difficult, regardless of material, because you’re not just dealing with width, you’re dealing with two height issues. The first is the height of the hands, just like an open face watch. The crystal must be higher than the hands, so as not to stop the watch via the hands rubbing on the crystal.

What type of Crystal Should you use in your pocket watch?

First of all, let me say that while I make clear recommendations below, the customer is my boss. I will do what you want with regards to crystal material. But people ask for my opinion, so I’m happy to give it below. If you disagree, I invite you to comment below – and I may even update the article if you teach me something I didn’t know.

Many of our customers are very conscious about material selection in their pocket watches. This is why we take the time to explain crystal options here. We’re also happy to discuss them in person or over the telephone with you if you have any questions or just want clarification.

To justify the use of one crystal style over the other is dictated by your needs summarized as follows: do you want form or function?

If you’re carrying your pocket watch daily, plastic is almost certainly the way to go. Plastic crystals are more durable than glass crystals – they will flex a little bit if dropped. This adds a small amount of cushion. Secondly, plastic doesn’t shatter in the same way glass does. I consider it to be safer because it won’t shard. Finally, plastic can, for light scratches, be buffed to look like new. Glass can technically be buffed, but it is honestly not practical and adds great expense to you, the customer.

In my opinion, glass should only be used when two criteria meet. The first criteria is that the pocket watch should be a display-only watch. You don’t want to carry the watch with a glass crystal because it if shatters in your pocket, you can really do some damage to the dial and hands (and, possibly, to you). Secondly, glass should only be used when authenticity is of utmost importance. Civil War Reenactors with 1857 Walthams, I’m talking to you! Ultimately, authenticity is only an issue on the oldest of American Pocket Watches, as by the 20’s and 30’s, plastic pocket watch crystals were becoming fairly common.

Hopefully we’ve explained your options on pocket watch crystals. If you have any questions, please feel free to comment below or to call us at 800-251-1484!