MY WATCH HAS RUBIES! BUT WHY?
THE USE OF GEMSTONES IN WATCHES
You may have a watch that is the jewel of your collection. Maybe several. But, did you know those watches might contain real gems? It's true, many watchmakers use rubies at strategic points in their movements, both mechanical and quartz.
How can you tell if your movement is one bedecked with this gemstone? Three ways come to mind;
1. The case back holds a wealth of information on your timepiece. Look for the word "jewels" and a number with it. That's how many rubies are used in your movement.
2. Check out the specifications in your watch manual. Again, look for the word "jewels."
3. If your watch has an exhibition case back, you probably can see some of the jewels. They'll be a delightful ruby red color. Like a fine claret, or ruby.
Like anything dealing with precious gems, more is better. How does the saying go? "You can't be too good looking, have too much money, or own too many gems." Okay, I added the gems part, but you get my drift. More jewels in a watch movement is a good thing.
Watch movements are intricate, micro-engineered marvels. The rotation of the gear train powered by the release of spring power works best when rotational friction is low. The finely machined shafts are held captive by equally precise holes in the various plates of the movement. Here's where one enemy of accuracy comes in, friction.
A metal shaft rotating in a metal hole will encounter friction. High friction can slow the rotation of the shaft and reduce the accurate display of time. So, what did watchmakers do to address this reality? What any good mechanical engineer would do, put oil on it.
As you can imagine, the amount of oil that can be applied is minuscule. In the early days of watchmaking, oils had some nagging problems. They would dry up, run off to other parts of the watch, turn gummy, or attract dirt and lose their lubricating quality. When the oil was new and fresh, accuracy was good. Over time, accuracy suffered as the protective oil began to fail.
Another consequence of rotational friction was wear that tended to enlarge the hole. Lubrication also reduced wear until it became ineffective. Wobbly shafts due to wear were additional enemies of accuracy and introduced a new problem, shortened longevity.
A BEJEWELED HISTORY
Now, you might think that crafting tiny ruby circles with holes for gear shafts is a modern development. After all, it must require advanced technology to manufacture them. Our ancestors continue to amaze me with what they could do with the primitive (by our standards) tools at their disposal. The first "jewel bearings," as they were called, for watches, were invented and patented in 1704 in England. Think about that, 1704! Those folks had great eyesight and steady hands.
At first, several different gems were used, including diamond, sapphire, garnet, and ruby. Eventually, the economics and characteristic of ruby made it the preferred choice. Natural gems were used until 1902 when Auguste Verneuil invented a process to make synthetic ruby and sapphire. The resulting jewels were cheaper and had all the properties of their natural counterparts.
So, what characteristics make ruby, real or synthetic, better solutions to wear and friction than oil and metal? Check out the following photographs taken through a microscope of steel (left) and ruby.
As you see, even finely finished steel has a rough surface. Ruby, on the other hand, is silky smooth. Pit smooth against friction, and smooth wins every time.
The other redeeming property of ruby is hardness. Sapphire is next in line to diamond on the Mohs Scale of Mineral Hardness. Just so happens, rubies and sapphires are cousins, sharing the family's toughness. Perfect for reducing wear.
Pictured to the left is a cross-section CAD drawing of a jeweled bearing with a shaft. It shows the jewel held inside one of the movement plates with the gear shaft secured.
And, next, we have a cool image of a jewel before final machining and insertion into a movement. Should I mention the image is not to scale? Nah, you get it.
MORE THAN JUST BEARINGS
While it's true the initial application for the jewel bearings was at points where shafts rotated in retaining holes, watchmakers soon found other applications, where they could take advantage of the jewel's wear resistance.
The following description from Wikipedia puts it very succinctly:
A typical fully jeweled time-only watch has 17 jewels: two cap jewels, two pivot jewels and an impulse jewel for the balance wheel, two pivot jewels and two pallet jewels for the pallet fork, and two pivot jewels each for the escape, fourth, third, and center wheels.
Did you notice the new term introduced by the Wikipedia excerpt? Of course, you did, "fully jeweled." Read on to find out what it means, and if it is an industry limitation.
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A LITTLE MORE ABOUT JEWELS
In the world of horology, a movement that has 17 jewels is termed fully jeweled. So, you might ask, if 17 is fully jeweled, does that mean there can't be any more? You can always have more jewels, and in the exquisite bespoke movements with every complication under the sun, you will find a few more than 17.
Take the world's most complicated watch ever built, the Vacheron Constantin Reference 57260. This one-of-kind watch boasts a staggering 242 jewels; two hundred and forty-two jewels! Now, that is fully jeweled!
Check out an image of this beauty below. By my count, there are 16 jewels in this photo alone.
What you need to take away from this discussion of jewels is this quality movement will use jewels at critical wear and friction points. Even high-end quartz movements may have a few jewels.
LIV is dedicated to delivering the best quality at accessible prices. As a result, we make every effort to use "bejeweled" movements where their characteristics meet the design requirements of a specific watch. The following table lists our movements and their respective jewel counts.
Can you get by without jewels? Of course, you can. However, why would you?
Everyone can use more jewels, even if they are tiny rubies in your watches.