Jewels in Movements?

[Marrk]

TRF is a rich source of information, knowledge and, sometimes, wisdom. We are all grateful for this.

Here are a few Watches 101 questions for the experts:

— Why are there jewels in watch movements?

— What do they do?

— Which jewels are selected and why?


Class is now in session. Teach me.

[Jocke]

Ok I try.

— Why are there jewels in watch movements? They get low friction to the axles, they
are very hard so they beat regular bearings. They never use to be replaced, if they do
they are damaged not outworn.

— What do they do? They works as bearings at the end of an axle.

— Which jewels are selected and why? Syntetic because they are cheap.

Jocke

[Terry Newton]

I was lazy. Here's your answer:

http://elginwatches.org/help/watch_jewels.html

Terry Newton

[abigsecret]

Originally Posted by Jocke

— Which jewels are selected and why? Syntetic because they are cheap.

It is indeed cheaper to use synthetic jewels over the real rubies they usted to use in the high end watches, but the price is not the only reason.
The real gemstones all have abbrasions and inclusions, which makes them more prone to breakage. The imperfections also makes it harder to cut out the perfect jewel bearing for a pivot. The synthetic jewels are perfectly consistant since they're man-made and therefore much more useful in a watch mechanism.

Another thing that is good to know about the amount of jewels, is that it doesn't matter how many jewels are in a movement, what matters is "if the movement is fully jeweled". What this means is that all the jewels are useful, and used in all of the right places.
You can have a movement that claims to have 50 jewels, while another one has 20 and still be just as good of quality, because those 20 jewels are used only and exactly there where needed.

According to Rolex all the 31xx movements have 31 jewels, yet the 3186 (GMTII) must have more than a 3130 (Airking) since there are more complications on that movement ...
I hope I'll find an answer to this claim one day, and when I do, I'll let you know!

[Tools]

Here's a great article.

Are 83 Jewels enough

[Ashley]

Good questions, great answers. Thanks for sharing your infinite wisdom, guys!

[Marrk]

Thank you Jocke, Terry, Mireyna, and Larry. Great link, Terry. Your laziness seems to be more instructive than my laziness!

This has been very informative and indeed has furthered my education.

[RW16610]

Originally Posted by Marrk

Your laziness seems to be more instructive than my laziness!

Glad to see you got the info you were looking for, this forum is great for that.