Pocketwatch 101℠ – Learn about Vintage and Antique Pocket Watches
All About Vintage Pocket Watch Crystals
Common Crystal Types and Styles
The piece of glass that covers the dial of your watch is called the crystal. That doesn't mean it's made of crystal, but "crystal" is the correct name for it. Original crystals for vintage pocket watches were typically made of mineral glass, and came in a wide variety of shapes, thicknesses and styles. We'll show you the more common styles (and a couple of less common styles) and provide a little information about how they were used.
Hunter Style or Geneva Crystal
If the watch has a hunter-case (with a metal cover over the dial and crystal) then the watch uses a hunter-style or Geneva-style crystal. Hunter-style crystals tend to be quite thin and fragile, and vary from almost flat to slightly convex, but all must be low enough to allow the metal case lid to close. One of the challenges of fitting a replacement hunter crystal is that it must be high enough to not touch the center arbor or interfere with the hands, and low enough to not interfere with the case lid. Sometimes there is VERY little clearance and finding a crystal that fits properly can be quite difficult.
Typical glass thickness for a hunter crystal is 0.4mm - 0.5mm, so they are quite thin and fragile. This is a great reason why you NEVER shut a hunter case watch with your big ol' thumb pressing right in the middle of the cover... if the clearance between cover and crystal is small, you're very likely to break the crystal!
Open Face Beveled Edge Crystal
Watches that have no case-lid over the dial of the watch are called "open-face". Many vintage pocket watches have open face crystals with a beveled outer edge, as shown below. The beveled edge was purely a stylistic choice, and gives the watch a crisp, sharply defined outline for the dial. Railroad pocket watches look great with beveled edge crystals.
Typical glass thickness for an open face beveled crystal is 1.0mm - 1.5mm, but can be up to 2.5mm.
Beveled edge crystal for open face pocketwatch
Open Face Smooth Edge Crystal
Open face crystals can also be smooth-edge or rounded-edge as shown below. Again, this was purely a stylistic choice. Based upon our observations, smooth edge crystals tend to be found on thinner, 12-size "gentleman's watches". As watches grew thinner, and as thinner watches became more stylish and popular, more attention was paid to a smoother transition between the crystal edge and the bezel.
Typical glass thickness for an open face smooth-edge crystal is 0.75mm - 1.0mm, usually just a little thinner than a beveled-edge crystal..
Smooth edge crystal for open face pocketwatch
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Open Face Flat-Thick Crystal
A lot of large, 18-size watches made in the late 1800's used flat-thick crystals. Whereas all the other crystal styles we've talked about are convex (domed), FT crystals are flat, or very nearly flat, on top. These crystals have a thick, pronounced beveled edge, which almost gives them a magnifying glass effect. A flat-thick crystal is definitely the right choice for many early 18-size watches.
Typical glass thickness for an open face flat-thick crystal is 3.5mm - 5.5mm.
Flat-thick crystal for open face pocket watch
English-Style High-Dome Bullseye Crystal
These high-dome crystals are typically seen on early English fusee watches. They have a flat spot ground into the center of the crystal which gives them a "bulls-eye" appearance. There is much debate among horologists as to the origin and purpose of the bulls-eye mark. Some believe it to be a mark left when the pontil rod is removed from the crystal during the manufacturing process, but there are many examples of smooth, concave glass objects from that time period which don't show a pontil mark, so that theory may not hold up. Some contend that it was to magnify the view of the watch, or direct more light onto the dial, but these theories don't seem to be supported by the empirical evidence. My personal opinion is that it was simply a matter of style, and that they came into vogue in about 1780, and went out of style in about 1820. Finding replacement rounded high-dome bullseye crystals is nearly impossible these days.
Open Face "American Bullseye" Crystal
These are similar to the English high-dome bulls-eye crystals, but they are much less domed and saw a brief return to popularity in the early 1900s.The bulls-eye on these later crystals is usually concave whereas it is flat on the early English style. Also called "Double Lunette with Cut Top" in the early watch material catalogs. Watches with original American bulls-eye crystals tend to be popular with collectors and often sell for premium prices.
Hard-to-Find Pocketwatch Crystal Sizes
Why are the some of the most common pocketwatch crystal sizes getting harder and harder to find? That's easy... it's because they are the MOST COMMONLY USED SIZES! Since there are no contemporary sources for vintage watch crystals, old-stock supplies are all we have left. For crystals sizes that were common across a wide variety of case brands, stocks of vintage crystals have been nearly depleted. There are some sizes we can no longer obtain in old-stock glass, and in those situations the only option is to use a modern acrylic crystal instead.
Expect to pay more for old-stock glass crystals in these tough-to-find sizes, as we are dealing with a very limited and dwindling supply of original vintage glass crystals.
Some of the toughest sizes to replace these days in open-face crystals are: 17/0 (386mm), 17/1 (387mm), 17/2 (389mm), 18/5 (416mm), 18/6 (417mm), 19/2 (431mm), 19/3 (433mm), 19/4 (434mm). (Sizes are in lignes, the archaic system in which old crystals are measured).
In Geneva, or hunter style, crystals the hardest crystals to replace are: 12/2 through 12/9 ( 275mm through 285mm), 14/12 (335mm), 14/13 (336mm), 18/3 through 18/7 (413mm through 419mm), and all sizes above 21/0.
Replacing Broken or Missing Crystals
At Renaissance Watch Repair, we have a large inventory of old-stock glass pocketwatch crystals in a wide variety of sizes and styles, including one of the largest inventories of American Bullseye crystals you'll find anywhere. We can replace MOST (but not all) vintage pocket watch crystals. In order to replace a missing crystal, the watch's bezel must be present. If the bezel is missing, there's no way to install a new crystal (for more info on cystals and bezels, read here).