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Who sells, makes or repairs the modern, quartz Gruen watches?

I have a vintage Gruen watch. How can I identify it?

How much is my watch worth?

Who can service or repair my mechanical Gruen watch?

How should I care for my mechanical watch?

What are the 'jewels' in a watch?

My Gruen movement has 'Conoruma' engraved on it. What does this mean?

What is Guildite?

What are the differences between 'gold-filled', 'rolled gold plate', 'gold reinforced with metal' and 'reinforced gold' watch cases?

Q: Who sells, makes or repairs the modern, quartz Gruen watches?

The Gruen Watch Company no longer exists. The company below sells the modern Gruen watches—contact them for quartz watch batteries, bands, and repairs.

I would not send them a vintage mechanical watch—find a good watchmaker, instead.

M. Z. Berger & Co.
33-00 Northern Boulevard
Long Island City, NY 11101-2215

(718) 472-7500

Customer service:


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Q: I have a vintage Gruen watch. How can I identify it?

Mike Barnett has painstakingly compiled a book identifying over 300 vintage Gruen models, including pictures, dates, original prices, and the price equivalents in today’s dollars.

He also publishes reproductions of Gruen parts catalogs, repair manuals and other Gruen material.

If your watch has a Gruen model 405, 410, 420, or 425 movement, Mike lists manufacturing dates by serial number on his website:

Mike also runs a forum where some exciting research on Gruen is being done.

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Q: How much is my watch worth?

Please don't ask me for estimates. I'm neither a watch dealer nor an expert on pricing old watches. Instead, find a vintage watch dealer or jeweler to evaluate your watch. Some dealers are listed on the Links page. There are also books available, such as the Complete Price Guide to Watches—see the Sources page.

Whether you use an appraiser or a guide book, be skeptical and get a second opinion. Few people, even vintage watch dealers and collectors, know very much about Gruen, so different price guides and appraisals will often give you wildly different prices for the same watch. All the price guides I've seen give incorrect names and dates for many of the Gruen watches they list.

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Q: Who can service or repair my mechanical Gruen watch?

You should be able to find a watchmaker in your area. In general, stay away from chain stores or shopping malls—it's best to look for an older, family-owned jewelry store with a watchmaker on the premises. Look for ads that list a 'certified master watchmaker.' Try to actually talk to the person who will work on your watch. A good watchmaker is a valuable resource, so you'll want to find someone you trust, and with whom you can build a long-term relationship.

A good place to start is the AWI (American Watchmaker's Institute), an organization that trains and certifies watchmakers. They have a searchable international directory to help you find watch and clock repair specialists.

American Watchmaker's Institute referral directory

Please keep in mind that most good watchmakers are extremely busy these days. It takes years of training and experience to become skilled in this profession—be patient and respectful.

Also, see the section below, How should I care for my mechanical watch?, for more information about watch serivce.

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Q: How should I care for my mechanical watch?

It's important to have your watch serviced about every five years. Just like a car or any other complicated machine, a watch needs fresh oil periodically—even modern, synthetic oils break down in a few years. The tiny parts inside a watch are under tremendous strain, and friction is their greatest enemy. When the ruby bearings get dry, they will efficiently grind away the softer steel parts. If it's been several years since the watch was last serviced, you could be causing damage every time you wind it.

Please, never wind an old watch unless you know its service history. Many vintage timepieces have mainsprings powerful enough to keep running even without lubrication—they might even keep good time while the movement quietly destroys itself.

It's wrong to believe that a watch is OK if it's simply been sitting in a drawer for years. In reality, one of the worst things you can do is to leave your watch idle for very long periods of time and then wind it. You're giving the oil time to break down, harden and get gritty; the parts will start wearing as soon as they start moving. If you have mechanical watches that you use only occasionally, do wind them at least once a month to keep the lubricants properly distributed inside. Don't let them sit idle for months or years—exercise is good for them. Either wind them regularly, or never, ever wind them

A watch service is called a "C-O-A" (Clean-Oil-Adjust). When properly done, the watchmaker will take the movement completely apart, clean and inspect the components, oil the parts individually with the correct oils (there are different lubricants for different parts), then put it back together and adjust it.

Many modern watchmakers will not dissassemble the movement, but will simply drop it in an ultrasonic cleaner, then give the whole movement generic lubrication. This will get a clogged watch running again, but without proper cleaning and lubrication, the watch's long-term health may be compromised. Grit in the bearings will continue to grind away. It's a good idea to ask a watchmaker about how the watch will be serviced, and to avoid this type of superficial service.

Also, keep in mind that a newly-purchased vintage watch may have had only a quick dunk in the ultrasonic cleaner, and will still need a real C-O-A if you want to wear it. The cost of service comes out of the seller's profit, so the seller will often do as little as possible to get the watch running.

On the other hand, I've also had very pleasant experiences with dealers who've taken great pride in bringing old watches back to life. Sellers who have watchmaking skills may do extra work themselves that it would be too expsive for them to pay someone else to do, when you consider the price they can sell the watch for.

If you need help finding a watchmaker, try the AWI referral directory, above. The AWI also has a page about watch care.

Gruen watches are very well made. In the 1910s and 20s, in particular, they were among the most expensive and highest quality watches sold in the United States. If they're taken care of, they will last practically forever, so there's no reason why you can't wear and use an old Gruen regularly.

For more information, see watch jewels.

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Q: What are the 'jewels' in a watch?

Industrial-grade or synthetic rubies are used to make a watch movement's bearings. A pair of these ruby 'jewels' hold the ends of the staff (axle) for each major wheel (gear); You can see some of these on the surface of the movement as tiny red doughnut shapes. The balance wheel, the most active moving part in the watch, usually has two jewels at each end of its staff; each pair fit together to form a single bearing with an oil-filled reservoir inside.

Rubies are almost as hard as diamonds. As long as the watch is properly lubricated, these smooth bearings are nearly friction-free, and are largely responsible for the many years of faithful service a mechanical watch can provide.

The ticking of a watch is the sound of two small jewels, each about the size of a pinhead, smacking into the steel teeth of the escape wheel. The loudness of these tiny rubies striking against steel hints at the huge stresses acting on these parts, relative to their size.

It's important to have a watch serviced about every five years. The ruby bearings are much harder than the steel parts they mate with; without oil, the steel will rapidly be ground away.

The jewels are not precious and have no value as jewelry; they're generally worth only a few cents each. There's no need to fear that a watch repairer will steal them.

The number of jewels in a watch is an indication of the design of the movement, but not necessarily of its quality. A cheaply-made 21-jewel movement may be less-accurate, more-poorly-constructed and shorter-lived than a well-made 15-jewel model. 15 jewels are sufficient to provide bearings for all the major moving parts; the most common configurations are 15, 17, 19 and 21 jewels. Gruen's handwinding Precision-grade movements have a minimum of 17 jewels; Gruen watches without the 'Precision' marking generally have 15 jewels. Automatic-winding watches and other complicated models may have 24 or more jewels because of the additional moving parts.

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Q: My Gruen movement has 'Conoruma' engraved on it. What does this mean?
A: Conoruma is Gruen's proprietary alloy used for balance wheels and hairsprings. The Hamilton Watch Company used a famous, similar material called 'Elinvar.' These alloys are designed to be stable in spite of temperature changes—they will expand or contract very little when the watch gets warm or cool. Because a watch is so delicate, changes in temperature will otherwise cause the watch to run slightly fast or slow. Balance and hairspring alloys like Conoruma help combat this problem.

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Q: What is Guildite?
A: Guildite (from 'Gruen Guild') is simply Gruen's brand name for a stainless steel alloy. Guildite was mostly used for watch cases. Some gold-filled watches also have Guildite backs.

Because human sweat and skin oil are acidic, corrosion-resistant materials are important for a wristwatch, which spends much of its time in contact with the skin. If you look carefully at vintage gold-filled watches, you can often find areas (especially at sharp corners) where the gold has worn away and skin acid has eaten into and hollowed out the brass underneath.

Early stainless steel alloys were developed in France in 1904 and England in 1912, but very few stainless steel consumer products were available until after WWI.

See the section below for more information on gold-covered watch cases.

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Q: What are the differences between 'gold-filled', 'rolled gold plate', 'gold reinforced with metal' and 'reinforced gold' watch cases?

Before materials like stainless steel became available, gold was used for watch cases because it doesn't corrode and doesn't cause allergic reactions after prolonged contact with the skin. (Some people have allergic reactions to metals like nickel and chrome; that's the reason for gold and surgical-steel posts on earings.) As an alternative to the expense of solid gold, cases were made of brass (or another 'base' metal) with a gold layer on the outside, which offered the same benefits.

Gold plating is by far the cheapest way to cover a watch case and gives the thinnest layer of gold; I don't believe that the original Gruen company made any gold-plated watches.

Rolled gold plate is made by a process that bonds a very thin layer of gold over base metal. This is thicker than gold plating but thinner than gold-filled. Gruen used this process when they started making lower-priced models in the 1950s.

A gold-filled case is a sandwich made from a slab of base metal between two thinner slabs of gold. The layers are bonded together under heat and pressure while being rolled out into a sheet and then formed into watch cases. The finished case is covered inside and out with a layer of gold, about 80 microns thick—about the thickness of a piece of copier paper. By comparison, the heaviest gold plating today is about 20 microns thick, one-quarter of this, and most gold plating is only about 5 microns, one-sixteenth as thick as the gold layer on a vintage gold-filled watch. Visually, gold-filled cases have a soft sheen like solid gold, while gold plating looks hard and shiny by comparison.

The disadvantage of a gold-filled, rolled-gold-plate or gold-plated case is that the gold will eventually wear through. Not only does this look bad, it allows the acids in the owner's skin oil and sweat to attack the case and cause corrosion.

Cases marked 'reinforced gold', 'gold reinforced with metal', or 'reinforced with extra gold' are a special kind of high-quality case, which I believe was unique to Gruen. Basically, these have a base-metal inner structure enclosed in a thick gold outer shell. Some of these cases have a gold layer on the inside; others do not.

Compared to a gold-filled case, a reinforced-gold case has a much longer-wearing finish. Inside the watch, where the gold layer is much less important, there is either no gold or a much thinner layer; the gold is all on the outside, where it does the most good.

Reinforced-gold cases were generally used on upscale models—in Gruen's product line, they fell between gold-filled and solid gold cases.

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