Cap jewel with what looks like a circular engraving around the edge

[Bill2024]

Hi All,

I’ve been cleaning a Tissot 27B-21 movement and the cap jewels on the top and bottom of the balance are different. The bottom jewel is what I’ve seen before, ie perfectly flat and shiny when clean. The top one though looks to have what appears to be a circle near the edge. It definitely won’t clean off and almost looks to be engraved.

Is this just another type of cap jewel that I’ve not seen before or is there a problem with it. 

thanks, Bill

Edited Tuesday at 04:57 PM by Bill2024

[mbwatch]

Yes - that type of jewel does exist and you will encounter it from time to time. I believe the groove cut into it provides an oil barrier, so lubrication cannot flow out away from the pivot.

I have no idea where replacements could be bought if you needed one though.

[mikepilk]

These are quite common. I don't know how that make the groove.  

I always use Fixodrop on the cap jewels to keep the oil in place, so the grooves aren't needed.

[Bill2024]

36 minutes ago, mbwatch said:

Yes - that type of jewel does exist and you will encounter it from time to time. I believe the groove cut into it provides an oil barrier, so lubrication cannot flow out away from the pivot.

I have no idea where replacements could be bought if you needed one though.

Interesting. It also seems strange that it’s only the jewel on the top of the balance that has the grove and not the one on the bottom. I guess maybe one of them got replaced at some point. 

29 minutes ago, mikepilk said:

I always use Fixodrop on the cap jewels to keep the oil in place, so the grooves aren't needed.

I’ve never used Fixodrop but I think it’s something I will look into to. Can I just ask how you use it when oiling the cap jewels?  

[nickelsilver]

14 hours ago, Bill2024 said:

 

I’ve never used Fixodrop but I think it’s something I will look into to. Can I just ask how you use it when oiling the cap jewels?  

I hold the jewel by its outside, dip in Fixodrop, lay it on paper and let it dry. With shock jewels, I then place oil in the center of the cap, and place the hole jewel in setting on top. With normal jewels, I assemble, and oil through the hole jewel.

[mikepilk]

I use Fixodrop on cap jewels, pallet stones and escape wheels.

I just hold the jewels in some Fixodrop for about 30s then let them dry. 

[VWatchie]

On 4/22/2025 at 7:10 PM, mikepilk said:

These are quite common.

I've never seen them, then again, I haven't got a ton of experience, but "common"? Really? In what context have you seen them? I'm not questioning you. I am sincerely curious why I've missed it.

On 4/22/2025 at 7:39 PM, Bill2024 said:

I’ve never used Fixodrop but I think it’s something I will look into to.

An alternative to Fixodrop is to apply less oil (no more than 50 % of the circle area). The only downside would be that it would shorten the service interval. More oil will prolong the service interval, but if the movement is subjected to trauma, there's a risk it will be displaced. Fixodrop makes it more stable. Unfortunately, Fixodrop is seriously expensive.

[caseback]

45 minutes ago, VWatchie said:

I've never seen them, then again, I haven't got a ton of experience, but "common"? Really? In what context have you seen them? I'm not questioning you. I am sincerely curious why I've missed it.

I've seen them on several swiss-made movements as well. Last one was a Tissot if I remember correctly.

[mikepilk]

1 hour ago, VWatchie said:

In what context have you seen them? I

In cap jewels on several watches I have serviced over the years.

I've recently serviced a couple of Longines movements where the cap jewels were colourless. They are a real pain. Without colour they disappear when immersed in any liquid for cleaning 

1 hour ago, VWatchie said:

Fixodrop is seriously expensive.

Not necessarily. Cousins do a 10ml bottle for £26 which will last me for years. That's just half the price of a simple Bergeon silicone cushion, so not too expensive 

[caseback]

5 hours ago, mikepilk said:

7 hours ago, VWatchie said:

Fixodrop is seriously expensive.

Not necessarily. Cousins do a 10ml bottle for £26 which will last me for years. That's just half the price of a simple Bergeon silicone cushion, so not too expensive 

And the "brand" bottles are still crazy expensive (£175) but knock-offs are about £20 on ali.. So for the price of 1 silicon cushion you're sorted..

[mikepilk]

3 hours ago, caseback said:

And the "brand" bottles are still crazy expensive

The 10ml bottle from Cousins is a big brand - Moebius

[Bill2024]

11 hours ago, caseback said:

I've seen them on several swiss-made movements as well. Last one was a Tissot if I remember correctly.

It was a Tissot movement I saw this one on; the 27b-21

[caseback]

56 minutes ago, mikepilk said:

The 10ml bottle from Cousins is a big brand - Moebius

I meant these:

2 minutes ago, Bill2024 said:

It was a Tissot movement I saw this one on; the 27b-21

Glad that my medium-to-short-term memory is still functioning ok

[Bill2024]

10 hours ago, mikepilk said:

In cap jewels on several watches I have serviced over the years.

I've recently serviced a couple of Longines movements where the cap jewels were colourless. They are a real pain. Without colour they disappear when immersed in any liquid for cleaning 

There were colourless cap jewels on an oris 581 KIF I was looking at. I was convinced I’d lost them when I put the jewel into heptane and couldn’t find the caps. I didn’t know colourless ones were a thing!

[mikepilk]

14 minutes ago, caseback said:

I meant these:

Yes they are a silly price. Fortunately the 10ml Moebius bottle has a metal gauze in the top, so no need for a separate bottle.

15 minutes ago, Bill2024 said:

I didn’t know colourless ones were a thing!

They shouldn't be!  Mad idea. I changed them for coloured ones

[VWatchie]

10 hours ago, mikepilk said:

Cousins do a 10ml bottle for £26 which will last me for years.

That's nice! Cousins do know how to make money in a way that benefits themselves and their customers. Repairing wouldn't be the same w/o them.

On 4/23/2025 at 10:00 AM, mikepilk said:

I use Fixodrop on cap jewels, pallet stones and escape wheels.

For most purposes, 10ml goes a long way. However, with a few exceptions, I’ve started applying Fixodrop to all parts that come into contact with grease or oil, so I went ahead and got the 100ml bottle. I just serviced a watch that I last worked on seven years ago, and to my surprise, it was practically dry—almost no oil left. I suppose it either evaporates or migrates over time?

I just now browsed the available options and noticed that Fixodrop 8981 ES/BS-10 (Ready to Use) is a bargain at just £104 per 100ml. Well, that is, compared to Fixodrop 8982 ES/BS-20 (Ready to Use), which goes for £850 per 100ml. According to ChatGPT, 8981 is intended for inexpensive watches serviced by enthusiasts, while 8982 is geared toward high-end timepieces handled by professionals. Or could it be that Moebius found a way to squeeze more money out of the same product? Hmm...

[mikepilk]

4 minutes ago, VWatchie said:

I just serviced a watch that I last worked on seven years ago, and to my surprise, it was practically dry—almost no oil left

That's strange. I re-serviced a couple of watches after about 4-5 years and there looked to be no loss of oil. These are watches I very rarely wear, and I probably over-oiled a bit back then. 

[nickelsilver]

33 minutes ago, VWatchie said:

I just now browsed the available options and noticed that Fixodrop 8981 ES/BS-10 (Ready to Use) is a bargain at just £104 per 100ml. Well, that is, compared to Fixodrop 8982 ES/BS-20 (Ready to Use), which goes for £850 per 100ml. According to ChatGPT, 8981 is intended for inexpensive watches serviced by enthusiasts, while 8982 is geared toward high-end timepieces handled by professionals. Or could it be that Moebius found a way to squeeze more money out of the same product? Hmm...

 

Note the 8992 is 850 pounds for a liter. I think this is really for industrial settings like they say, where it would be used as a final bath in a 20,000 buck cleaning machine. I use the 8981.

26 minutes ago, mikepilk said:

That's strange. I re-serviced a couple of watches after about 4-5 years and there looked to be no loss of oil. These are watches I very rarely wear, and I probably over-oiled a bit back then. 

 

That is excellent- I don't often get to see a serviced watch 5 years later, but when I do I expect to see pretty much the same oiling on the balance jewels as when it went out. I think at that area, being essentially sealed, it really should remain fairly pristine for likely 10 years. It's why some makers go to the trouble to use cap jewels on the escape wheel as well- not so much for friction reduction, but to keep the oil longer where it really counts.

[VWatchie]

53 minutes ago, nickelsilver said:

Note the 8992 is 850 pounds for a liter.

That was observant! I completely missed that, and it explains everything. Thank you!

1 hour ago, mikepilk said:

I re-serviced a couple of watches after about 4-5 years and there looked to be no loss of oil.

That's great! Admittedly, there's a big difference between 4 years and, in my case, 7.5 years to be more precise — but still. Also, I was early in using my stereo microscope during oiling and extremely careful not to over-oil. I actually think — even if it sounds unlikely — that I tend to under-oil.