Why rubbies?

[rolley7]

Why are rubies used in a watch movement?

[kanikune]

It's harder than steel.

[powerfunk]

According to my layman's understanding, they're placed where friction occurs so as not to wear out, as metal inevitably would.

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[GradyPhilpott]

This may be of help:

http://en.wikipedia.org/wiki/Jewel_bearing

[cop414]

Hmmm, once again I've been schooled by TRF!

[kieselguhr]

Magic rubies?

[ZakSgp]

Actually they are synthetic now, only older watches use genuine jewels.

[padi56]

Originally Posted by rolley7

Why are rubies used in a watch movement?

Now in the mid late 1960s the watch jewel war started,my watch has more jewels than your watch etc,some boasting 100 jewels most just for decoration..Now today 15 jewel and 17 jewel movements are mostly manual wind.But most auto movements today are 21,23 or 25 and above,now a 15 or 17 Jewel can be just as accurate as 31 or more.Usually the synthetic rubies used today which act as Jewel bearing and capstones used in balance wheel and wheel pivots plus pallet fork, at critical wear points, these are only needed on the friction moving parts.But having more jewels don't mean that movement is better that one with less.Its a bit like today's computer hard/drives now getting bigger daily but bigger don't always mean its better.Now today the synthetic Ruby red jewels in the watch are man made even in Rolex, (I should say grown),and the same for the synthetic sapphire crystal they are man made but they too a grown under laboratory conditions .

Below is picture of a Waltham of the period boasting 100
jewels but in reality only 17 in the actual movement.Its is
possible the the jewels in the rotor could have helped the winding rotor wind more efficiently. But IMO would seriously doubt it just a boast that I have more and I am better than you complete and utter pure hype marketing I call it brain washing.



Cap Jewels


Hole Jewels.

Pallet Fork Jewels.

[Tools]

Originally Posted by rolley7

Why are rubies used in a watch movement?

They're not really "rubies", they are synthetic sapphire (in red/ruby). these jewels are used as low-friction, replaceable, contact surfaces.. (bearing surfaces)

Check out Tip #12 in the Amateur Watchmakers Corner:

https://www.rolexforums.com/showthread.php?t=44158