Polishing a sapphire crystal with 0.25µm diamond paste - any experience?

I have spotted some very fine (thin spiderweb) scratches on my sapphire crystal. Looks like it’s made contact with a wall or something but must have been just a graze as they are so light. The scratches can only be seen in certain lighting conditions and cannot be felt with a finger nail. I’ve read some posts on here where members have achieved some great results on much worse scratches using various grades of diamond paste. I think mine are so fine I could go straight to the 0.5 or 0.25 micron options.

Does anyone have any advice or experience? Could I achieve an improvement using just a cloth and some elbow grease? I have to stress these are very fine scratches. Also, if I don’t use a dremel or similar tool would it be possible to distort the crystal if I was to concentrate on polishing the affected area? I’m assuming so little material will be removed that it won’t weaken the crystal or the WR rating (300m) of the watch.

The sapphire only has internal AR.

Thank you.

Firstly whats the watch case is it Swiss, Japan etc?

If theyre really fine, try metal polish. I had a distinctly visible scratch on a Rolex sapphire and rendered it much less visible by the careful application of Brasso on a soft cloth (just elbow grease, no Dremel). At its next service it was rendered near invisible.

If you do try that, be sure not to get any down the side of the crystal.

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Originally Posted by Bry1975

Firstly whats the watch case is it Swiss, Japan etc?

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Longines Legend Diver. Replacement cost of crystal is £711.98 not including fitting!

To be fair the scratches are so fine they aren’t really noticeable unless you go looking for them. I’m swinging towards just letting it be.

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Originally Posted by monogroover

If theyre really fine, try metal polish. I had a distinctly visible scratch on a Rolex sapphire and rendered it much less visible by the careful application of Brasso on a soft cloth (just elbow grease, no Dremel). At its next service it was rendered near invisible.

If you do try that, be sure not to get any down the side of the crystal.

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Thanks for that. Yes very fine and interesting that brasso could be enough!

Interesting.

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Originally Posted by Bry1975

Mr T for £700 you could make a whole batch of sapphires, is the crystal profile PLANO, Double dome, single dome etc?

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Tell me about it!

I’m assuming it’s double domed but still no idea why they are so expensive. To be fair it really doesn’t need replaced as it looks completely fine in day to day use and not even noticeable in most cases.

Possibly dumb question but are you sure they are scratches and not marks on any external AR coating?
I polished the AR off the outside of one of Sinn 903s as it got badly marked over time.

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Originally Posted by Sinnlover

Possibly dumb question but are you sure they are scratches and not marks on any external AR coating?
I polished the AR off the outside of one of Sinn 903s as it got badly marked over time.

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Yeah, no external AR on this one, just internal. I think I’m more inclined just to leave it as is. They really aren’t noticeable in everyday wear and even then it’s only in certain light that you can see them if looking for them.

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Originally Posted by Mr Tetley

Longines Legend Diver. Replacement cost of crystal is £711.98 not including fitting!

To be fair the scratches are so fine they aren’t really noticeable unless you go looking for them. I’m swinging towards just letting it be.

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Good Lord. That price is completely divorced from reality: what are they smoking?!

I understand a bit of mark-up, but for something as humdrum as a sapphire crystal - part only, no less - that seems quite ridiculous.

Presumably they’re insisting on a service at the same time?

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Originally Posted by Mr Tetley

Longines Legend Diver. Replacement cost of crystal is £711.98 not including fitting!

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Good God.

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Originally Posted by Idontgram

Presumably they’re insisting on a service at the same time?

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Nope. That price is just for a crystal. Madness.

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Originally Posted by Mr Tetley

Nope. That price is just for a crystal. Madness.

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Is it at all possible that this could be some sort of mistake on their part? It’s hard to comprehend.

you will very likely do more harm than good so i would leave it

polishing usually involves a multi stage process since you need one grade to cut down past the marks and other grades to polish back up

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Originally Posted by Fullbreakfast

Is it at all possible that this could be some sort of mistake on their part? It’s hard to comprehend.

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I had heard the price of the LLD crystal was extortionate (a few other posts online about it) so I sent an email to STS asking for a quote:
£711.98 including vat for the part (REF L319155409)
Fitting £67.00 including vat.
Plus 18.00 postage.

As I said, the scratches are very very fine and really not noticeable on my watch so I’m happy to leave it. I just hope I never actually damage the crystal!

I’m sorry to hear about his, but that crystal cost is extortion!

D


Sent from my iPad using Tapatalk

Having read this thread and finding myself in utter disbelief at the cost of the sapphire I got in touch with Longines this morning to ascertain the actual cost direct with them. Here is there response.

Dear Mr. Clapperton,

Thank you kindly for your message, I hope you are well.

I am pleased to advise I can offer you a number of options.

I can despatch a prepaid pack to the address requested for you to send this to us for examination. Please provide your preferred address then allow 5 working days for delivery.

We will then look to run an examination on this to see if a service is needed. A price list will be included within your prepaid packaging as standard alongside your packaging kit. Should your timepiece be covered under its service warranty, please kindly provide a copy of your sales receipt or warranty card in the space provided.

I have looked into this for you and can confirm that the RRP of the Crystal for your timepiece is £646.61 , if a service is need this will be fitted as past of that, if its just the replacement, then a fitting fee of £35 will be added.

Any further instructions or comments you may have in regards to the repair of your watch, please do include on your form so our watch technicians may be advised of your requests upon receipt of your timepiece.

Upon receipt and following technical analysis, we shall contact you to advise our findings and the next steps and raise an estimate for the work needed to complete this. Please look out for your customer service log in details once the watch has been received.

To view our current price list, please visit https://www.longines.com/en-gb/customer-service/services/maintenance-prices

Alternatively, you can return your watch through your nearest point of sale which can be found at https://www.longines.com/retailers

If you have any additional queries, please do not hesitate to contact us.

Kindest regards,
Harriet

Harriet Stewart
Customer Care Advisor

good grief - whats special about this crystal ? i would have thought that any competent independent watchmaker could measure and just replace with a generic? (i have a non date legend diver myself)

other than that i'd just leave it alone , when ppl realise its going to take some time to remove scratches they usually get the dremmel out and the heat ends up cracking the crystal.

So if that’s including VAT they are around £60 cheaper than STS. Bargain. Mine is also the 36mm version so I was expecting it to be a little less expensive.

LLD owners, protect your crystal. :-)


Ps. I’m leaving mine as is. The scratches are really too fine to be bothered about.

Absolutely insane pricing.

They really must be on crack.

Another model of watch thats going to be avoided . How can Longines justify such a huge cost for one glass ?! Attempted robbery nothing more

I bought various grades of diamond pastes(Pack) of amazon for my G-Shock.
Cheap enough & sorted it.

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Originally Posted by Tomaitch

Another model of watch thats going to be avoided ...

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My thought exactly - I've often admired this model, and it was on the long-list; not any more. Indeed, I'd be very wary of Longines in general now.

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Originally Posted by Mr Tetley

I had heard the price of the LLD crystal was extortionate (a few other posts online about it) so I sent an email to STS asking for a quote:
£711.98 including vat for the part (REF L319155409)
Fitting £67.00 including vat.
Plus 18.00 postage.

As I said, the scratches are very very fine and really not noticeable on my watch so I’m happy to leave it. I just hope I never actually damage the crystal!

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You’ll probably never need another one, thankfully. But it’s still a shocker. Shameful exploitative behaviour from Swatch Group.

Has anyone compared the Rdunae compressor R3 sapphire profile and size?

This is the level of scratching I’m talking about. Impossible to capture all the very faint ones which are around the same area between 4 and 5 marker but as you can see it certainly doesn’t need replaced even if the crystal cost substantially less.

They can’t even be seen in the top photo:

https://i.ibb.co/3kkkmRQ/IMG-8567.jpg

https://i.ibb.co/fnkcY6M/IMG-8566.jpg

https://i.ibb.co/vLQPHNR/IMG-8568.jpg

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Originally Posted by Mr Tetley

This is the level of scratching I’m talking about ...

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Just imagine you spaff the thick end of £800 on fixing these almost invisible abrasions ...





And then you go and do it again... :hororr: :hororr: :hororr: :hororr: :hororr: :hororr:

Just not worth it. Wear it, enjoy it - treat it as a palimpsest upon which to engrave a chapter of your life :encouragement:

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Originally Posted by earlofsodbury

Just imagine you spaff the thick end of £800 on fixing these almost invisible abrasions ...

And then you go and do it again... :hororr: :hororr: :hororr: :hororr: :hororr: :hororr:

Just not worth it. Wear it, enjoy it - treat it as a palimpsest upon which to engrave a chapter of your life :encouragement:

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Once I discovered the cost of a new one, replacing wasn’t an option. £5 on diamond paste would sort it but don’t think I’m even going to bother with that incase I manage to make it worse (which is highly likely given my level of DIY skill).

I can 't believe the price quoted for a replacement crystal, possibly the quote includes servicing the watch and refinishing the case?

My advice is to either leave it alone or carefully polish with fine diamond paste, always work along the length of the scratch.

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Originally Posted by walkerwek1958

I can 't believe the price quoted for a replacement crystal, possibly the quote includes servicing the watch and refinishing the case?

My advice is to either leave it alone or carefully polish with fine diamond paste, always work along the length of the scratch.

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Price was definitely just for the part. It didn’t even include fitting, that was extra.

Do you rub the polish in a circular motion or back and forth?

Take a look here https://r.tapatalk.com/shareLink/top...ink_source=app


I couldn't find my thread but toddys is just as good.

PS

I think the Longines price might include the case, I only say this because I actually enquired about a crystal for a Heritage Diver & was quoted around £285.00 HOWEVER they managed to destroy mycase and replaceed it during a service but the sapphire crystal was included already fitted in the case.
According to them all cases come with the crystal already fitted.

I just can't think of any other reason why the cost is so high.

Sent from a technical device

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Originally Posted by walkerwek1958

I can 't believe the price quoted for a replacement crystal, possibly the quote includes servicing the watch and refinishing the case?

My advice is to either leave it alone or carefully polish with fine diamond paste, always work along the length of the scratch.

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Believe it ! Glass only

This is perfectly normal now for a Swatch group brands. Omega domed sapphires are now £600 plus and have been for a few years. The flat or less domed ones are approaching £250+. It’s obscene but it’s their policy across the board. I’ve had very good results with diamond paste on light scratches but it takes time, you can even use a Dremel as long as you are careful about heat as it takes an age by hand. Personally I found no result polishing along the scratch but working at 90 deg from both sides worked best.

Do these have anti-reflective coating on the top of the crystal or just on the underside?
Polished scratches that were a bit more severe than that with 0.5μm lapping paste by hand on my PRS3 a few years ago, I remeber that it was a bit tedious but it worked.

I hadn't realised how expensive this Chinese stuff was getting.

Crazy price difference.
https://www.seikomods.com/shop/ct096/

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Originally Posted by Padders

This is perfectly normal now for a Swatch group brands. Omega domed sapphires are now £600 plus and have been for a few years. The flat or less domed ones are approaching £250+. It’s obscene but it’s their policy across the board. I’ve had very good results with diamond paste on light scratches but it takes time, you can even use a Dremel as long as you are careful about heat as it takes an age by hand. Personally I found no result polishing along the scratch but working at 90 deg from both sides worked best.

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My non-existent watch budget will no longer be spent on Swatch Group products. I trust they will be suitably chastened.

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Originally Posted by Fullbreakfast

My non-existent watch budget will no longer be spend on Swatch Group products. I trust they will be suitably chastened.

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:smile-new: That'll learn em!!!

SERIOUSLY if the Longines watch is desirable I'd consider making the sapphire but only one size 39mm case or 42mm case, sapphire would be 1:1 reproduction.

Regards

Bry

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Originally Posted by Mr Tetley

This is the level of scratching I’m talking about. Impossible to capture all the very faint ones which are around the same area between 4 and 5 marker but as you can see it certainly doesn’t need replaced even if the crystal cost substantially less.

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Honestly think those would come out completely, or at least invisibly with a bit of effort + Brasso, pretty easily. You won't deform the crystal. Would mask off the rest of the watch and use it sparingly.

Price quoted is totally shocking as is the Omega

The way things are heading with restricted supply to watchmakers, insistence on full services etc I can see more and more people moving away from traditional watches.

Most young people are now wearing smart watches and over time these will only get better as technology moves on.

Ten or Twenty years from now the traditional wrist watches could be a thing of the past similar to the pocket watch.

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Originally Posted by boring_sandwich

Price quoted is totally shocking as is the Omega

The way things are heading with restricted supply to watchmakers, insistence on full services etc I can see more and more people moving away from traditional watches.

Most young people are now wearing smart watches and over time these will only get better as technology moves on.

Ten or Twenty years from now the traditional wrist watches could be a thing of the past similar to the pocket watch.

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Agree 100% , I've banged the drum about the restrictive practices for several years, now that parts and service costs have reached silly levels people are,starting to see why! Restrict parts, squeeze the lifeblood out of the repair trade, then ramp prices up..........just as I predicted.

I think the traditional wrist watch will go into serious decline over the next few years, difficult to make out a rational case otherwise.

I have used diamond polish on a Panerai Saphire crystal and it worked like a charm. No need to worry it wil end up worse. The diamond polish won't scratch up the crystal. It will come out...Removed a dull antireflective coating from a crystal as well using a dremel and polish..just perfect.

Best,
Guillermo

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Originally Posted by torromoto

I have used diamond polish on a Panerai Saphire crystal and it worked like a charm. No need to worry it wil end up worse. The diamond polish won't scratch up the crystal. It will come out...Removed a dull antireflective coating from a crystal as well using a dremel and polish..just perfect.

Best,
Guillermo

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Originally Posted by monogroover

Honestly think those would come out completely, or at least invisibly with a bit of effort + Brasso, pretty easily. You won't deform the crystal. Would mask off the rest of the watch and use it sparingly.

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Thanks for that.

I think I was concerned about 'over polishing' and leaving a distortion/indentation in the crystal. I guess if I'm not planning using a dremel or similar tool and only polish by hand this would be almost impossible to do.

Ok, if I try removing these very fine ‘scratches’ should I just polish the affected area or should I polish the entire surface of the crystal? I’m considering starting with 0.25 micron diamond paste since they are very very fine.

Just the affected area. The important thing is not to get any of whatever you use to polish it down the side of the crystal.

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Originally Posted by monogroover

Just the affected area. The important thing is not to get any of whatever you use to polish it down the side of the crystal.

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Thank you. The box sapphire should allow me to avoid going down the side. I just won’t go too close to the edge and give it a good rinse when finished. That’s if I actually decide to do it!

I’ve taken out a hell of a lot worse, that was unnoticeable afterwards. I can’t temper the grades of paste, but I used two fine grades, with one being the finest I could find at the time to finish.

Tape off the bezel and go over with Dremel like tool with the paste, will take 2 mins if that (see link to my post above where I did it with my PO, scratch was a lot worse than yours).