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Thread: Polishing a sapphire crystal with 0.25m diamond paste - any experience?

  1. #1

    Polishing a sapphire crystal with 0.25m 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.

  2. #2
    Master
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    Firstly whats the watch case is it Swiss, Japan etc?

  3. #3
    Master
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    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.

  4. #4
    Quote Originally Posted by Bry1975 View Post
    Firstly whats the watch case is it Swiss, Japan etc?
    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.

  5. #5
    Quote Originally Posted by monogroover View Post
    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.
    Thanks for that. Yes very fine and interesting that brasso could be enough!

  6. #6
    Master
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    Interesting.
    Last edited by Bry1975; 11th February 2024 at 23:39.

  7. #7
    Quote Originally Posted by Bry1975 View Post
    Mr T for 700 you could make a whole batch of sapphires, is the crystal profile PLANO, Double dome, single dome etc?
    Tell me about it!

    Im assuming its double domed but still no idea why they are so expensive. To be fair it really doesnt need replaced as it looks completely fine in day to day use and not even noticeable in most cases.

  8. #8
    Grand Master Sinnlover's Avatar
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    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.

  9. #9
    Quote Originally Posted by Sinnlover View Post
    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.
    Yeah, no external AR on this one, just internal. I think Im more inclined just to leave it as is. They really arent noticeable in everyday wear and even then its only in certain light that you can see them if looking for them.

  10. #10
    Craftsman
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    Quote Originally Posted by Mr Tetley View Post
    Longines Legend Diver. Replacement cost of crystal is 711.98 not including fitting!

    To be fair the scratches are so fine they arent really noticeable unless you go looking for them. Im swinging towards just letting it be.
    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.

  11. #11
    Presumably theyre insisting on a service at the same time?

  12. #12
    Master
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    Quote Originally Posted by Mr Tetley View Post
    Longines Legend Diver. Replacement cost of crystal is 711.98 not including fitting!
    Good God.

  13. #13
    Quote Originally Posted by Idontgram View Post
    Presumably theyre insisting on a service at the same time?
    Nope. That price is just for a crystal. Madness.

  14. #14
    Master
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    Quote Originally Posted by Mr Tetley View Post
    Nope. That price is just for a crystal. Madness.
    Is it at all possible that this could be some sort of mistake on their part? Its hard to comprehend.

  15. #15
    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

  16. #16
    Quote Originally Posted by Fullbreakfast View Post
    Is it at all possible that this could be some sort of mistake on their part? Its hard to comprehend.
    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 Im happy to leave it. I just hope I never actually damage the crystal!

  17. #17
    Master helidoc's Avatar
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    Im sorry to hear about his, but that crystal cost is extortion!

    D


    Sent from my iPad using Tapatalk

  18. #18
    Grand Master
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    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


    Cheers,

    Ben



    ..... for I have become the Jedi of flippers


    " an extravagance is anything you buy that is of no earthly use to your wife "

  19. #19
    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.

  20. #20
    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.
    Last edited by Mr Tetley; 12th February 2024 at 15:12.

  21. #21
    Grand Master TheFlyingBanana's Avatar
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    Absolutely insane pricing.

    They really must be on crack.
    So clever my foot fell off.

  22. #22
    Craftsman
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    Another model of watch thats going to be avoided . How can Longines justify such a huge cost for one glass ?! Attempted robbery nothing more

  23. #23
    Grand Master
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    I bought various grades of diamond pastes(Pack) of amazon for my G-Shock.
    Cheap enough & sorted it.


  24. #24
    Master earlofsodbury's Avatar
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    Quote Originally Posted by Tomaitch View Post
    Another model of watch thats going to be avoided ...

    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.

  25. #25
    Master
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    Quote Originally Posted by Mr Tetley View Post
    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 Im happy to leave it. I just hope I never actually damage the crystal!
    Youll probably never need another one, thankfully. But its still a shocker. Shameful exploitative behaviour from Swatch Group.

  26. #26
    Master
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    Has anyone compared the Rdunae compressor R3 sapphire profile and size?

  27. #27
    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:






  28. #28
    Master earlofsodbury's Avatar
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    Quote Originally Posted by Mr Tetley View Post
    This is the level of scratching Im talking about ...

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





    And then you go and do it again...

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

  29. #29
    Quote Originally Posted by earlofsodbury View Post
    Just imagine you spaff the thick end of 800 on fixing these almost invisible abrasions ...

    And then you go and do it again...

    Just not worth it. Wear it, enjoy it - treat it as a palimpsest upon which to engrave a chapter of your life
    Once I discovered the cost of a new one, replacing wasnt an option. 5 on diamond paste would sort it but dont think Im even going to bother with that incase I manage to make it worse (which is highly likely given my level of DIY skill).

  30. #30
    Grand Master
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    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.

  31. #31
    Quote Originally Posted by walkerwek1958 View Post
    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.
    Price was definitely just for the part. It didnt even include fitting, that was extra.

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

  32. #32

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

    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
    Last edited by sickie; 12th February 2024 at 20:31.

  33. #33
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    Quote Originally Posted by walkerwek1958 View Post
    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.
    Believe it ! Glass only

  34. #34
    Master
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    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.
    Last edited by Padders; 13th February 2024 at 08:58.

  35. #35
    Craftsman
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    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.

  36. #36
    Master JDB's Avatar
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    I hadn't realised how expensive this Chinese stuff was getting.

  37. #37
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    Crazy price difference.
    https://www.seikomods.com/shop/ct096/

  38. #38
    Master
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    Quote Originally Posted by Padders View Post
    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.
    My non-existent watch budget will no longer be spent on Swatch Group products. I trust they will be suitably chastened.
    Last edited by Fullbreakfast; 13th February 2024 at 16:08.

  39. #39
    Master
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    Quote Originally Posted by Fullbreakfast View Post
    My non-existent watch budget will no longer be spend on Swatch Group products. I trust they will be suitably chastened.
    That'll learn em!!!

  40. #40
    Master
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    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

  41. #41
    Master
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    Quote Originally Posted by Mr Tetley View Post
    This is the level of scratching Im 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 doesnt need replaced even if the crystal cost substantially less.
    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.

  42. #42
    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.

  43. #43
    Grand Master
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    Quote Originally Posted by boring_sandwich View Post
    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.
    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.

  44. #44
    Craftsman
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    Diamond polish!!

    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

  45. #45
    Quote Originally Posted by torromoto View Post
    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
    Quote Originally Posted by monogroover View Post
    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.
    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.

  46. #46
    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? Im considering starting with 0.25 micron diamond paste since they are very very fine.

  47. #47
    Master
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    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.

  48. #48
    Quote Originally Posted by monogroover View Post
    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.
    Thank you. The box sapphire should allow me to avoid going down the side. I just wont go too close to the edge and give it a good rinse when finished. Thats if I actually decide to do it!

  49. #49
    Ive taken out a hell of a lot worse, that was unnoticeable afterwards. I cant temper the grades of paste, but I used two fine grades, with one being the finest I could find at the time to finish.
    It's just a matter of time...

  50. #50
    Master
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    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).

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