All About Watch Crystals - Watch and Learn #2

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  • Опубликовано: 17 янв 2025

Комментарии • 296

  • @c.toobitz7566
    @c.toobitz7566 3 года назад +9

    This series is gold, thank you so much. I always wanted to learn about watches, but not on a professional level, just as a hobby.

  • @Sparks68
    @Sparks68 8 лет назад +15

    Well done on the crystal materials. Some years ago from the late 1960's through the 1980's Seiko coated the acrylic crystals on some of their upper end lower tier and their mid-tier watches with a material that hardened the surface to nearly the same as mineral glass. Seiko had a proprietary name for it that I've not been able to find. I've got two vintage Seiko with this crystal material. They cannot be polished like standard acrylic or Hesalite and are extremely durable and scratch resistant, looking just about like they did when new 35-40 years ago. They were overtaken by Seiko's Sapphlex (a sapphire coated hardlex) and Hardlex when those became economically viable for the upper end of lower tier watches. Sapphlex similarly was discontinued as the cost of sapphire dropped. There is a reason for acrylic and Hesalite being used on military watches. Unlike mineral glass and sapphire, it doesn't shatter. It can be scratched, chipped and gouged, but it's much more difficult to crack or break compared to mineral and sapphire as it flexes on impact. In addition, they're easily molded with a dome shape eliminating the mirror effect a dead flat crystal has which is a light and reflection discipline killer They've got a duller surface finish even when new that reduces the specular highlights under sunlight and other strong light sources.

  • @tjkeller6109
    @tjkeller6109 3 года назад +1

    Just started looking into collecting and I know nothing about watches. The first two videos are great and will continue watching and liking the rest. Thank you for the work you put in.

  • @kirkdarling4120
    @kirkdarling4120 2 года назад +1

    Your "Look and Learn" videos are so informative and easy to understand. Thank you.

  • @RonaiHenrik
    @RonaiHenrik 6 лет назад +7

    7:25 Hmmm please correct me if I am mistaken but normal glass is more shatter-resistant than sapphire due to it being less stiff (lower number on Mohs scale of hardness). Sapphire is harder, more difficult to scratch, but because of this reason it shatters easier too, it's not as good in putting up with vibration.

  • @2TheAbbeyClinic
    @2TheAbbeyClinic 7 лет назад +54

    Another great instruction vid from you. Thanks.
    Can't believe this is free, like going to college for watches.

    • @islandwatch
      @islandwatch  7 лет назад +9

      Haha, I'll take your college savings money :)

  • @carlitoxb110
    @carlitoxb110 3 года назад

    These watch and learn videos are so valuable for us beginners to the hobby of watch collecting, I appreciate your effort teaching these concepts

  • @robbabcock_
    @robbabcock_ 5 лет назад

    Fascinating! I'm going back to watch all the Watch & Learn segments!

  • @pootthatbak2578
    @pootthatbak2578 3 года назад

    Great, simple advice..just restoring a steeplechase mens watch by concord..i am pleased to report my crystal is sapphire. The cool to the touch, and beading water confirmed it. Thank you so much.

  • @gunslinger11bravo
    @gunslinger11bravo 8 лет назад +24

    the Russian made Vostok Amphibia 200m divewatches use a domed plastic crystal that is actually designed to increase the water resistance of the watch. As depth increases the crystal deforms and actually presses harder on the gasket underneath it. this along with a similar method used on the screw-down case back allows the watch to become more water resistant the deeper it goes.

    • @islandwatch
      @islandwatch  8 лет назад +11

      Great observation. Sort of like how an arch is the most efficient engineering structure. A dome is just a 3 dimensional arch.

  • @PukaHeadMan
    @PukaHeadMan 4 года назад +1

    That Sinn is a killer watch! Great informative video. Thank you for posting!

  • @ilyaibragimov6255
    @ilyaibragimov6255 8 лет назад +1

    Really thorough. Thank you Marc for this series, really looking forward to what you have in store!

  • @Claus-L.Mueller
    @Claus-L.Mueller 8 лет назад +1

    Very interesting. Especially the "Lotus Effect". The only disadvantage of sapphire is it's brittleness. It's very scratch resistant but it's likely to crack if it hits a hard surface.

    • @Sparks68
      @Sparks68 8 лет назад +1

      I've found sapphire to be extremely durable. They're generally made thick enough to withstand some impacts during normal wear. They can be gouged or chipped if banged against a very sharp and hard object. They can be shattered, but all the watches I own with sapphire would have to be hit extremely hard to shatter the crystal.

  • @roygardiner2229
    @roygardiner2229 6 лет назад +1

    Thank you. I am learning something new with each episode.

  • @allenjanes5976
    @allenjanes5976 8 лет назад +18

    thanks. I found the water test most interesting.

  • @Sanjuro313
    @Sanjuro313 Год назад

    Thanks Mark! These series are great!

  • @powertube5671
    @powertube5671 6 лет назад

    The water test was fascinating. I also ordered some Polywatch.

  • @wargamingrefugee9065
    @wargamingrefugee9065 8 лет назад +2

    Hello, Great series, thanks for taking the time to make it for us. Here's a request and a couple of pieces of information. The request first: You said you had your Sinn for ~10 years. How often should a mechanical watch been taken in to be serviced (cleaned and lubricated)? Also, since quartz watches have moving parts, and some even have jeweled bearings, should they be serviced too? And now a couple of factoids: First, the tube, cylinder or dowel shaped thing which sapphire crystals are cut from is called a "boule". Next, if a person is wants to know if their watch has a plastic crystal as opposed to one made of glass or sapphire, there are a couple of fast and fun tests. They can see if their crystal shows finger prints easily. If it does, then it is not plastic. Another test is to place the crystal of their watch on their forehead. If it feels cold, like the metal back of the watch, then the crystal is glass/sapphire. If it feels warm, as opposed to the metal case back, then the crystal is plastic.

    • @islandwatch
      @islandwatch  8 лет назад +7

      Great information. Thank you! I come from the camp that says "if it ain't broke, don't fix it". My Sinn has never been serviced, its the most accurate watch I own. Ditto with quartz. Though quartz watches, like autos, can indeed be overhauled. I know I'm in the minority where this is concerned, but I feel that there's much more that can go wrong by removing 50 parts and then putting them back, then if you didn't do anything in the first place. If it needs service because its not operating correctly, then of course, service it.

    • @wargamingrefugee9065
      @wargamingrefugee9065 8 лет назад

      Thanks Marc.

    • @tejasmodiadv
      @tejasmodiadv 7 лет назад +1

      Long Island Watch thanks

  • @GunCollector007
    @GunCollector007 5 лет назад

    Thanks. Just ordered some poly watch for a vintage IWC.

  • @buzzufy
    @buzzufy 3 года назад

    This is a great video, glad to learn the basics of watches. Thank you for the video.

  • @2DRINKSMINIMUM
    @2DRINKSMINIMUM 8 лет назад +45

    do the different types of leather for straps! or just the different types of straps.

  • @DAM1EN666-0
    @DAM1EN666-0 8 лет назад

    Great video as always! Another thing to keep in mind(surely you just forgot to mention) is that the bigger the diameter of the crystal, the more expensive it also becomes. Keep'm coming!

  • @allanredford6070
    @allanredford6070 3 года назад

    great video, Marc.
    just got a Pulsar, very flat, nearly flush crystal, . Hardlex mineral with incorpoated boron.
    very clear view, maybe some coating. my watch solar, black textured dial,gold hands,indexes, lumed.. told that gold tone links, dial ring, hands,indexes, all PVD'd
    is it true saphire more prone to shattering on an impact?
    why is Pulsar, Seiko's mid-range brand ignored by you guys - experts?- cos all quartz-based?
    Pulsar designs different to Seiko collections. my 3rd one, all AOK.-accurate,strong, well finished.
    I, for one would like to see some review-tests on them,

  • @1cookgs
    @1cookgs 4 года назад

    Great information. I really enjoyed learning about watch crystals.

  • @timrobinson3241
    @timrobinson3241 8 лет назад

    Having watched some of your interesting videos, I'm now going through the series from the start! There's always stuff to learn: I didn't know about the water droplet test. Very interesting. The late UK antiques expert Arthur Negus used to test porcelain by gently tapping them on his front teeth. It can give an indication of a watch crystal too. Having said that, doing either that or just tapping with a finger on the Hardlex of my Seiko SKX007, it sounds/feels more solid than one of my sapphire crystals..! Thanks for a great series Mark (Marc?). Regards. Tim.

  • @yasyasmarangoz3577
    @yasyasmarangoz3577 4 года назад +1

    18 minutes and it completely was worth my time!
    I lowkey hoped that you'd destroy them to show us how resistant they're, but you've probably payed for them so I can understand it...

  • @JonathanGrandt
    @JonathanGrandt 4 месяца назад

    This was a great video. Very informative. I feel like a nerd.

  • @philipallen2730
    @philipallen2730 8 лет назад

    Excellent as usual Marc. How about a video on servicing are there different levels

  • @Hobby-zn7ce
    @Hobby-zn7ce 4 года назад +1

    Great vid especially the water test info. Are there different levels of hardness with the sapphire crystal?

  • @hemanthpaularigela4773
    @hemanthpaularigela4773 Год назад

    Hi mark. I learned so much from your videos about watches. They are very interesting. Recently I've purchased 350$ divers watch from MVMT. They claimed that the watch have sapphire.ive tested it in a diamond shop and it was showing sapphire. But once I've bumped it on a wall tile and it got scratched. Does sapphire really scratch?

  • @roadshowautosports
    @roadshowautosports 2 года назад +1

    I’d assume one shouldn’t buy a watch that has a sapphire Crystal cracked, since it takes a really hard hit to break them, and would be very possible damage to the movement, do you agree? Awesome video, with simple language.

  • @abhishek_banyal
    @abhishek_banyal 8 лет назад

    Excellent Video. I have a Seiko Hardlex front and back on mine. Not as good as Sapphire but remain flawless to this day.

  • @Geoduck.
    @Geoduck. 7 лет назад

    Much appreciated Mark. Now I have a clear idea in regards to crystals.

  • @mlast3264
    @mlast3264 2 месяца назад

    Thanks for putting this together

  • @cjm0125
    @cjm0125 8 лет назад

    Great video! Super informative! Can you do a video on the different types of movements, and the pros and cons of each?

  • @polarroller4848
    @polarroller4848 8 лет назад

    Great channel. How about a video on water resistant testing of watches during manufacture. Do they test deeper than they specify on watch cases etc...

  • @bassfishingwiththeantichri2921
    @bassfishingwiththeantichri2921 7 лет назад +5

    So what you're saying is to take heed from your friends painful tale of woe and always be sure to have a "no diamonds" policy set forth prior to engaging in any type of physical activity that may endanger the sanctity of your sapphire crystal. It sounds reasonable to me. Will do!

  • @bmw128racer
    @bmw128racer 3 года назад

    The water droplet test was fascinating.

  • @Younk13
    @Younk13 8 лет назад +1

    Great info as always. I would love a video explaining how to use GMT. Recently purchased one and I'm confused lol

  • @thomasellis1814
    @thomasellis1814 2 года назад

    Wow omg I love this video!, especially the water hack

  • @socoblue1988
    @socoblue1988 6 лет назад

    Your content is top-notch, sir.

  • @mikethebike67
    @mikethebike67 8 лет назад

    Great series! Really enjoyed it so far.

  • @lindakorthanke4242
    @lindakorthanke4242 4 года назад

    Hello there!!! Thank you so much for your videos, Ive been watching them for almost 2 hours now. You are a kind person for sharing your talents, I been picking up watches at estate sales and want to add it to my many interests how to fix them when I retire from my job next year!!!
    My question to you or maybe a watch and learn? Some of the watches i purchased have no batteries in them nor have written any where battery size info. What would be the best way to get batteries that would work best?

  • @miguelteixeira5438
    @miguelteixeira5438 Год назад

    The water trick actually works thank you 😊

  • @ricktemmen6272
    @ricktemmen6272 5 лет назад

    Mark, somehow I missed this one. I'm glad I caught it now. Very Interesting. Thanks 😎👍

  • @gregalonzo747
    @gregalonzo747 7 лет назад

    I would like to about mineral crystals that have a sapphire coating. Is it durable? How long does the coating last? Great series, thanks for sharing your time knowledge.

  • @gregalonzo747
    @gregalonzo747 7 лет назад

    I have a few questions, what about mineral crystals that are sapphire coated? Is it really a plus? How long does the coating last? Can it be reapplied? By the way, I love the Watch and Learn series. You share important information and in an entertaining manner)))

  • @zzyzxzee6374
    @zzyzxzee6374 8 лет назад

    Enjoy your series,thanks!

  • @stileshumphrey4195
    @stileshumphrey4195 3 года назад

    Thanks Marc for the lesson! 👍

  • @raymondmalone9721
    @raymondmalone9721 8 лет назад

    Very interesting video Mark, love these type of videos , simple but great to watch and learn as title states.👍
    Beginners guide to movements ...

  • @Alex-di8ti
    @Alex-di8ti 6 лет назад

    Hi Marc, it would be great to see a watch and learn on removing and treating crystal scratches :)

  • @artl52
    @artl52 8 лет назад

    Nicely done! Would like to see more info (video) on the parts of mechanical watch - how the gear train works and what each piece does. Thank you

  • @robertocastillo2260
    @robertocastillo2260 3 года назад

    Did you know how to polish the cyclops of a Rolex to eliminate the scratches?, thanks!!!

  • @parisryan5950
    @parisryan5950 2 года назад

    very helpful tips, thanks!

  • @SmokeRingsPipeDreams
    @SmokeRingsPipeDreams 6 лет назад +2

    Which resists shattering more, mineral, or sapphire?

    • @islandwatch
      @islandwatch  6 лет назад +2

      Mineral would be more forgiving in an impact scenario.

  • @josephj6521
    @josephj6521 5 лет назад

    Cheers! 👍 Hydrophobic, now that’s a great way to describe the sapphire crystal. 😉

  • @osemekeugbo999
    @osemekeugbo999 8 лет назад

    Brilliant, very educative. As an engineer + watch enthusiast, its great to combine my two passions, just as you do. Great video, hope there is plenty more of this series to come.
    + I live in the UK and I have just discovered that you are capable of shipping watches to the UK. So glad I've found a place where I can buy brand new mechanical pieces from a trusted online source.
    best regards, James

  • @hocklaikhor8353
    @hocklaikhor8353 8 лет назад

    Great video! There are many different type of case back like screw down etc. Can you maybe cover this and what its impact on water resistant? Also, which one is the best? Thanks.

  • @lesgarten
    @lesgarten 4 года назад +1

    That Sinn Chronograph was freakin' awesome!

  • @XFS540
    @XFS540 Год назад

    If it could be done, how expensive would it be to replace an acrylic crystal with a sapphire crystal?

  • @normroberts3468
    @normroberts3468 8 лет назад

    Cool video does gravity affect balance wheels in automatic watches

    • @islandwatch
      @islandwatch  8 лет назад

      Absolutely it does! That is why watches are "adjusted" to positions.

  • @munawarhussain9859
    @munawarhussain9859 8 лет назад +6

    great video very informative ........other video suggestions type of moments auto,manual wind,solar powered.quartz, kinetic.
    or another suggestion watch types dive,flight dress, field................love your content .

    • @islandwatch
      @islandwatch  8 лет назад +1

      Thank you. Great suggestions! Noted.

  • @adbraham
    @adbraham 7 лет назад

    There is an easy way to tell sapphire from mineral; based on sapphire, being crystalline in structure, being a much better conductor of heat than glass . . . This is easiest to do when you have a 'control' watch with a known material used for the crystal. You can try this for yourself with two watches; one sapphire, the other mineral: leave both watches on a surface well away from heat (even body heat), for a few moments to equilibrate, then simply pick up on after the other and touch the 'glass' briefly against your lips. The sapphire will feel noticeably colder than the glass. This is only really useful when you have control watches of known material as it relies on the perceived difference between the two materials

  • @jmahaney3
    @jmahaney3 3 года назад

    Marc, can a cyclops window be added to any crystal or just the sapphire?

  • @ryanstafford8544
    @ryanstafford8544 8 лет назад

    Awesome, love the series so far!

  • @dandumitrescu8545
    @dandumitrescu8545 7 лет назад

    Great video! I understand that the Sapphire is the best material. But the better choice is to have Sapphire with AR only on the inside not on exterior and inside, correct?

    • @islandwatch
      @islandwatch  7 лет назад +1

      Correct.

    • @dandumitrescu8545
      @dandumitrescu8545 7 лет назад

      Thanks! I have one more question. I like very much Orient Monarch FDD03001W0. I see that it has a mineral crystal and I want to know if this can be replaced with a sapphire one. I mean, a watch that normally is sold with mineral crystal can have a sapphire one instead? (sorry for my bad English)

  • @wizardofahhhs759
    @wizardofahhhs759 4 года назад

    My Citizen watches have Swarovski crystals and my Luminox has sapphire crystal. I've found that the Citizen crystals are pretty much scratch resistant.

  • @Klockwood1
    @Klockwood1 6 лет назад +1

    I’m a welder and with anything but sapphire I have a problem of if a spark hits the crystal it will actually melt it and leave a little divot where the spark hit it

  • @JimboJones2022
    @JimboJones2022 5 лет назад +2

    I'm trying to get a green crystal replacement for my milgauss. I am looking for the best quality and closest to the gen without purchasing through rolex.

  • @mostirreverent
    @mostirreverent 3 года назад

    You can easily scratch the anti-reflective coating. Also some coating give off a blue hue. I’m not sure what the different types of coatings.
    Different materials will give a different contact angle which is the amount of spherical nature of the drop, Based on hydrophobicity

  • @coffeeisgood102
    @coffeeisgood102 8 лет назад +10

    Because plexi glass can be easily repaired I prefer those. I use baking soda and water and use toilet paper to rub it with. The crystal comes out like from the factory. On my Omega Speedmaster which sports a sapphire, it will keep the scratch for the rest of it's life. I wish Omega had used plexi glass on that watch. Great video. Keep them coming.

    • @islandwatch
      @islandwatch  8 лет назад +6

      Thanks! Toilet paper, who would have guessed!?

    • @kargi42
      @kargi42 7 лет назад +1

      Harold Bullock The Original Moonwatch Speedmaster still has haselite.

    • @pericodelospalotes5738
      @pericodelospalotes5738 6 лет назад

      What did you do??? Sapphire crystal is almost impossible to scratch, did you fall from a motorcycle or any other serious accident? I once suffered exactly that and my Eco-drive Citizen got scratches in its titanium case and bracelet but the sapphire crystal remains perfect. I never wear mechanicals riding my motorcycle because the vibrations could damage the mechanism.

    • @pborgia1
      @pborgia1 3 года назад

      My 1967 pre-moon Speedmaster still has its Hesalite crystal and it is beautifully clear. I have buffed out scratches a few times with Noxon or Flitx metal polish. They work great. Also Omega still uses Hesalite on the Speedmaster moon watch.

  • @orangewheels01
    @orangewheels01 5 лет назад

    Hi mark, I've watched this video a couple of times now, very interesting, is the cyclops saffhire as well as the crystal? Many thanks.

  • @grumpybollox7949
    @grumpybollox7949 3 года назад

    this makes me wanna buy a new watch every episode

  • @scottsteibel
    @scottsteibel 4 года назад

    I grew up on Long Island, the watch information is interesting, but your Long Island accent so reminds me of home.
    Be well.

  • @SChristmas-he2vx
    @SChristmas-he2vx 10 месяцев назад

    Excellent Sir!

  • @vicever08
    @vicever08 3 года назад

    I just check reflection and compare it with known mineral glass or sapphire, but only works for crystal without AR coating.

  • @anthony.catbagan
    @anthony.catbagan 3 года назад

    I've seen "convex crystal glass". What is that? Mineral or Acrylic?

  • @lndyrd
    @lndyrd 3 года назад

    i have tiny scratches on my Islander Great Wave Samurai which is why i came here. I am surprised because it is sapphire (and i don't have any diamonds that could scratch it). Does this mean the AR coating is on the outside and is what got scratched?

  • @wescobts
    @wescobts 5 лет назад

    Excellent video

  • @bwhite-ee
    @bwhite-ee 8 лет назад

    Great job especially on your setup for the water test. I was surprised just to see it so clearly, the clear water sliding/smearing off a clear surface.

  • @mohdhaq640
    @mohdhaq640 5 лет назад

    Really appreciate your effort

  • @user-cq5fb7cd2b
    @user-cq5fb7cd2b 2 года назад

    Hi Long Island Watch. I have two watches with a mineral crystal. However when I do the water drop test, the water leaves no trial and resembles the effect a water drop has on a sapphire crystal. How is this possible?

  • @hyperchord
    @hyperchord 8 лет назад +90

    Him and his fiancé were "holding hands," sure . . .

  • @tongp1108
    @tongp1108 3 года назад

    thanks for a great review man !

  • @FelipeCerdaBarra
    @FelipeCerdaBarra 8 лет назад

    Great video! Loved the part where you do the tests with water.

  • @596laroussi
    @596laroussi 4 года назад

    Thank you very informative video.

  • @henrikpettersson2886
    @henrikpettersson2886 5 лет назад

    This chanel is excellent.

  • @MrChipBryant
    @MrChipBryant 6 лет назад

    Thank you for sharing your knowledge!

  • @stevefarmer15
    @stevefarmer15 8 лет назад

    Nice video Mark, very informative, thank you. Keep them coming,
    regards.

  • @SmokeRingsPipeDreams
    @SmokeRingsPipeDreams 8 лет назад

    Nice video, well done!

  • @wpherigo1
    @wpherigo1 6 лет назад

    These are great, Marc!

  • @prasannahhentsmogan1308
    @prasannahhentsmogan1308 7 лет назад

    Awesome vids. Very educational. Subscribed.

  • @paulsteele6120
    @paulsteele6120 5 лет назад

    Well Mark, you being in the watch game will know that the difference in cost per unit is not that great, however the harder the crystal it becomes difficult (in fact, almost impossible) to shape. As with"doming" ,if you want that affect especially on vintage watches you will have to go "plastic". However like many things that go on in the watch trade "all is not clear," excuse the pun! A rough and ready way is like checking diamonds against "paste". The sapphire due to it' crystal lattice construction just like diamonds will feel cool against your cheek as against plastic which always feels err 'uncool' even when it comes straight out of the fridge. Someone, was saying the other day about the hardness testing watch crystal glass using a Vickers hardness tester, don't think I'd like to be around as the diamond point is pushed into the glass surface, it would be spectacular (sorry for that pun as well).

  • @yourdata2478
    @yourdata2478 7 лет назад +2

    Another very informative video thanks for the time, and your effort Mark.👍
    ⌚⌚⌚⌚⌚ five watch star's 👏🖖

  • @genehollon6989
    @genehollon6989 6 лет назад

    VERY INTERESTING INFORMATION.I have a Rolex I am having a sapphire crystal installed.

  • @leonardc1303
    @leonardc1303 8 лет назад

    It is good information and appreciated. Liked and subscribed.

  • @paulhiggins4111
    @paulhiggins4111 4 года назад

    Hi Mark , I just bought a Piaget polo s ...water resistant to 100 meters but does not have a screw crown . I would like to swim in the ocean to a depth of 10 to 20 feet and dive off the back of the boat 🚣‍♀️. Should I be concern that damage will occur? Thx Paul

  • @valueink
    @valueink 8 лет назад

    Great video Mark! Learned a lot from it, and I thought I knew enough about crystals :)
    What is the model of the Sinn watch? It's beautiful. Do you sell those? Thanks.

    • @islandwatch
      @islandwatch  8 лет назад

      That is a Sinn 757 UTC Chrono. We don't sell Sinn. Sorry.

  • @xanderdaneel3286
    @xanderdaneel3286 7 лет назад

    Can you please explain to us how mineral crystals with sapphire coating works? Whats the scratch resistance and AR level?

    • @islandwatch
      @islandwatch  7 лет назад

      Mineral sapphire coating I think is more gimmick/marketing than anything. The under material is still mineral, so still prone to scratch.

    • @xanderdaneel3286
      @xanderdaneel3286 7 лет назад

      Yes thank you. Do you have any idea how it is applied on top of the mineral glass? And really how scratch resistent it is? Also more or less the price difference between the normal mineral and the mineral with the sapphire coating?

  • @Vv20vV
    @Vv20vV 6 лет назад +2

    Is it possible to purchase sapphire crystals for a watch that was made with mineral? I own several watches that has mineral crystals, but would like to replace it with sapphire.

    • @karategk1
      @karategk1 6 лет назад

      I own a citizen eco drive with their usual soft mineral crystal that is terribly scratched up. I asked if Citizen service center if I could have them put a sapphire crystal on it, and they said the watch case would not support sapphire. But I'm not paying Citizen $100 to put another crappy mineral crystal. I'd rather buy a hardlex crystal and try putting it on myself.

    • @justincourtney8691
      @justincourtney8691 6 лет назад

      In some cases yes.
      I put an AR treated sapphire crystal in my seiko SKX.