Are these synthetic rubies? (FHF 97)

[MartinOfPrague]

Hello, are these going train stones synthetic rubies, or is it some different material? I hope the difference from the traditional balance wheel jewel is visible enough on the photo. My main concern is, can I clean bridges with these "jewels" in normal cleaning fluids?

All right, so if I can assume from the photos I found online, synthetic rubies are translucent, while these are not. What are they, then? To my unexperienced eye, they look more like a red plastic.

[Nucejoe]

Are you sure they are rubies? can be plastic bushings.

[MartinOfPrague]

3 minutes ago, Nucejoe said:

Are you sure they are rubies? can be plastic bushings.

I am not. Sorry, English is not my native language and I used "rubies" in more generic meaning, like "bearings". All right, so plastic bushings they are, probably. The point is the writing on a bridge says "15 jewels", so I did not expect plastic bushings where jewels should be.  

[KarlvonKoln]

Hello Martin.  I looked very closely at your pictures.  That is very strange.  I have seen many strange things inside watches, but I have not seen bearings like those before.  I own a watch with an FHF 97 in it, and the rubies did not look like those.

I am forced to wonder if an amateur repair person replaced all those bearing with red plastic.  Those movements would not be made that way.

[JohnR725]

If you look at your balance jewels that's what the jewels should look like.

If there plastic they should be soft enough to be scratched with steel like corner of a screwdriver tip. Then if it does scratch like plastic I'd keep it out of the cleaning fluid as you have no idea what kind of plastic it is.

Then the Swiss do have another form of synthetic Ruby called Polyruby. As far as I know the only place you find this is in pallet forks I don't think I've ever seen or heard of it being used as a bearing jewel.  on pallet forks you recognize it as pink colored stones that are not transparent.

[MartinOfPrague]

21 hours ago, KarlvonKoln said:

I am forced to wonder if an amateur repair person replaced all those bearing with red plastic.  Those movements would not be made that way.

Hi Karl, I believe I am the first owner of the movement. I bought it (just the movement, there was no watch) as a part of watchmaking lessons kit from certain semi-online watchmaking school, 15-20 years ago, not sure. Never touched it until recently, though. So it is probably a "study" or "practice" version of the movement, where jewels were replaced with plastic bushings for the sake of cost-cutting. Still, I find it ridiculous - how am I supposed to learn inspecting the jewels here?

9 hours ago, JohnR725 said:

If there plastic they should be soft enough to be scratched with steel like corner of a screwdriver tip. Then if it does scratch like plastic 

Thanks John. I tried to scratch it and it scratches very easily, just like plastic, so it is probably safe to assume it IS plastic, much as I refused to believe it first.

Edited February 6 by MartinOfPrague