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My watch collecting days go back to the mid 70's but I've been collecting + restoring Seiko's for many years. My favorite model: The Yellow Dial 6139-600X as most of you probably already know. I was able to buy one brand spanking new back in 76' as a kid with my first "Real" paycheck fresh out of high school. She was a beauty and I was hooked. Fast forward 30 years and I was heavily engaged in collecting and restoring Seiko's. Back then original crystals were plentiful. Nowadays, not so much. There have been many aftermarket crystals available. Some are good copies. Some are not so good. Needless to say I've tried all the popular ones.
I've been contemplating, for quite some time, to step up to the next level, and do a reproduction 330W18GN crystal of my own. After all, it's the crystal I use to most. For a little background on the 330W18GN Mineral Glass Crystal there are 3 versions.

The first and early version is the crystal with the outer ring and was only used for a few months up until about April or May of 69' in the Speedtimer Proof models. I have only run across this style mounted in a watch and have never seen one as a replacement crystal. The later crystals will interchange with this style crystal.




The next version was a Double Domed version which was used from mid 69' up until roughly mid 73'. From mid 73' on the 3rd version was a inner domed Flat Top version. Since most aftermarket 330W18GN's are the flat top version I wanted to reproduce the earlier Double Domed crystal. Several months ago I contacted a "supplier" to inquire about a custom crystal order. After submitting a sample of a NOS Early Style Original Seiko 330W18GN Double Domed Crystal the process moved forward. Being a perfectionist has it's advantages and disadvantages. I wanted to get this right. My biggest complaint was the inner bezel distortion caused by most aftermarket 330W18GN crystals. If you haven't noticed it before you'll know what I'm referring to after this review. It turns out, as I had imagined, the manufacturing end of a reproduction crystal would be a lengthy process. After much discussion, research, development, and revisions, my reproduction crystal has became a reality. This review is not to claim I have a perfect 1:1 copy that "is available nowhere else" but rather an in depth study of the aftermarket crystals that are available and how they measure up to the original. You'll have to judge for yourself which you prefer.......:


This review will only cover Mineral Glass Crystals. Personally, I would never consider a Plexiglass Crystal in place of a Mineral Glass Crystal.
I prefer to stick with the original design. If a watch originally came with a mineral glass crystal then that's what I'll use if a replacement is needed. The same goes for an acrylic crystal. If that is what was used originally, I wouldn't attempt to replace it with a mineral glass crystal.
These are the 4 Most Popular specimens up for review along with mine for a total of 5 crystals: In order, The Original, My reproduction, Sekosis, Sternkreuz, and Spencer Klein's.




For this review, I used the same watch, I did my best to keep it in the same position, using the same camera angle with the camera mounted on a tripod so we would be comparing apples to apples.

Original Double Dome 330W18GN Crystal . There's not much to say other then Seiko got this Right! Crystal clear view of the dial and inner bezel with no distortion.


First up is Klein's (Klien's Vintage Watch) repro 330W18GN crystal. This was originally reproduced by Jonathan Koch at East Tech Manufacturing. It is the late style Flat Top crystal. Johnathan actually participated in it's development at G+S supply in Rochester NY. Jonathan spent several months at G+S supply, hands on, in it's development. It's a good crystal but it has it's shortcomings. Particularly noticeable is the inner bezel distortion and the "black ring shadow" around the inner bezel when viewing the watch straight on.
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Next up is the Sekosis reproduction 330W18GN crystal. It's another "Flat Top" crystal. It looks good at first glance. It's another popular seller due to its lower price but when tested fell short of desired results. On the positive side there was only a light touch of the black ring shadow around the inner bezel as seen on the KVW crystal. Inner bezel distortion was acceptable but the overall measurements, which will be shown later in this review, fell short of the original. This was the only crystal that "fell out" once the bezel was removed and the watch was turned over to remove the crystal. With the original crystal and the other crystals tested, a light push from the back side with slight resistance noted, was required to remove the crystal.


Then we have the SternKruez 330W18GN crystal. In my opinion it's has been one of the better choices when it comes to reproduction 330W18GN crystals. It is a Double Dome crystal. Just a slight hint of ring around the inner bezel, only at certain angles, and the overall measurements are more in line with the original. However, it does have a slight bit of inner bezel distortion compared to the original. I'd say over the years I've used an equal amount of Jonathan's original "East Tech" crystals and the Sternkreuz crystals on my own watches and on restorations done for others.




And finally here is my reproduction 330W18GN crystal. A Double Dome Tempered Mineral Glass Crystal. No black ring shadow and not much, if any, inner bezel distortion when compared to the original. I'm a stickler for details and I feel it measures up well to the original. No Bogus claims here. No Hype. Just a good honest alternative to an original crystal when an original isn't available or is over priced. It has passed the test of a Persnickety WIS Collector for Fit, Finish, Appearance, and Pressure Testing up to 100 meters.



 

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Discussion Starter #2
Continued:

The overall measurements are shown below. Please keep in mind there can be slight variances between crystals of any manufacturer and even two crystals from the same manufacturer can vary slightly in their measurements.



Now, lets review the Specifications of the original when it comes to overall diameter:
First up: the Original 330W18GN crystal




Next up: Klein's 330W18GN crystal. It measures up well compared to the original regarding outside diameter.





Next up: Seikosis 330W18GN crystal. As far as I'm concerned the overall outside diameter falls short of the original and I would personally have concerns about this with it's fit against the "L" shaped crystal gasket and it's ability concerning water resistance. Just "my personal" opinion.





Then we have the Sternkreuz 330W18GN crystal. It's right on the money with the Original 330W18GN crystal.



And finally, here's my reproduction 330W18GN crystal. It's also right on the money with the original.


Lets look at the overall crystal height measurements. We can only compare the Original, the Sternkreuz, and My crystal because they are the only Double Dome crystals in the review. For Klein's and the Seikosis crystals we'll compare them to an original Flat Top crystal. To get an accurate measurement I had to use a straight edge on the bottom of the crystal which measured 0.86mm thick. So, for the actual height we'll have to subtract the thickness of the straight edge from the overall height of the crystal.



Once again we'll start off with the Original 330W18GN crystal. 4.64mm - 0.86mm we get a 3.78mm for crystal height.





The Sternkreuz 330W18GN measures 4.74mm - 0.86mm for a crystal height of 3.88mm.




My 330W18GN crystal measures 4.74mm - 0.86mm for a crystal height of 3.88mm. The same as the Sternkreuz crystal.



Now lets compare the Flat Top crystals.
First up is an Original 330W18GN00 Flat top crystal. 420mm - 0.86mm for a crystal height of 334mm





Klein's Flat Top 330W18GN. 435mm - 0.86mm for a crystal height of 3.49mm.




Finally the Seikosis Flat Top 330W18GN crystal. 443mm - 0.86mm for a crystal height of 3.47mm





Are we done yet?? Heck no! In the world of Persnickety WIS Wisdom there is more.........:) Lets look at the bottom edge of the crystals.


Original on left: frosted on the bottom edge. Klein's on the right: polished on the bottom edge. It's a little hard to tell in the photo but if you're in doubt check one yourself.



Original on the left,frosted on the bottom edge. Seikosis on the right. Polished on the bottom edge and noticeably thinner in width then the original.




Original on left, frosted bottom edge. Sternkreuz on the right. polished on the bottom edge.




Original on left, frosted on bottom edge. Mine on the right, frosted on bottom edge.......




Now for a side profile comparison with an Original 330W18GN crystal:


Original on the Left, Klein's on the Right




Original on the Left. Seikosis on the Right




Original on the Left. Sternkreuz on the Right.



Original on the Left. Mine on the Right.




Finally, there is the pressure testing. Obviously, the original crystal doesn't need to be pressure tested. I have previously tested the Klein crystal and the Sternkreuz crystal and they have passed the 6 ATM (203.4') wet pressure test. I have not tested the Seikosis crystal but I have tested my new crystal and it has passed the 203.4' wet water resistance test.
The industry standard is to test the watch case with no movement inside for obvious reasons such as a catastrophic failure of some sort. I've simply included the movement to show my confidence in this crystal. We start off by placing the watch in the air portion of the chamber and pumping the pressure up to 6 ATM. the watch is left in this position for about 10 minutes.If the watch doesn't hold pressure, The pressure will enter the watch at this point. Then the watch is lowered into the water in the chamber at which point the pressure in the chamber is released. If the watch has a leak it will be seen in the form of a stream of bubbles leaving the watch at the point of the leak. In that case you'd be able to pinpoint the source of your leak. So, first we'll see the watch in the chamber with the pressure pumped up to 6 ATM as shown in the photo:




Then the pressure is released as shown on the gauge. This is where the rubber meets the road. No signs of any bubbles means my crystal and my gaskets have passed the pressure test although I have since learned quite a bit more about pressure testing as you'll see below.




To take the testing a step further I sent one of my crystals to a friend of mine for independent testing. He subjected my crystal to several different tests on professional testing equipment that I don't have access to. One was a wet vacuum test of -.8bar in which it passed. Next were 2 separate pressure tests. The first was a 60 Meter Wet Pressure Test and then a 100 Meter Wet Pressure Test. Each test was followed up by a Condensation Shock Test. My crystal Passed all the tests it was subjected to.
Since I'm just learning what a Condensation Shock test is all about I'll quote my friend who has the experience to explain the procedure:

"The condensation test really isn't that complicated. It should be thought of as a necessary part of water testing, as merely the absence of visual water present inside a case after pressure testing isn't enough to say scientifically that no moisture got inside the case. If the crystals were tested in a true laboratory/watch service setting, they should have gotten the condensation test as part of that regimen. Just going into a 6atm wet pressure chamber, and then coming out, doesn't mean that some moisture didn't get in, and wouldn't do so over the long term in actual use in water. The condensation test proves that it didn't, and gives one a little more confidence that the case is as sealed as it needs to be."
"Typically, the condensation that forms after shocking the warm case with a cold temp to the center of the crystal should last for no more than 60 seconds."


I think I've covered all the bases when it comes to the research and development behind my reproduction crystal followed up by intensive testing to insure a quality product.



The only thing left was the packaging. I tried to put as much thought into the packaging as in the development of the crystal. I like a "complete package". Thankfully, my Wife is a little more Tech Savvy then myself. We were able to create a label that was Worthy of this crystal and not just some generic packaging...........





Many of you have already seen my new crystal Unbeknownst to you..... I was fortunate to have been able to install one of my sample prototype crystals in Kyle's (BigBlueKyle) 6139-6002 Sunrise Speedtimer a couple months back as featured here:

https://www.thewatchsite.com/21-japanese-watch-discussion-forum/333221-little-sunrise-your-viewing-pleasure.html


He was excited to give one a try when I shared this project with him. He had the following comments concerning the crystal after he viewed his watch in person:


"Hi Tom,
Looking at the Sunrise Dial through your New 6139 Crystal I have already noticed differences/improvements as compared to the other crystals. Clarity is much better. Distortion is less. Outside reflections picked up in your New crystal are less - I did not expect this but your New Crystal has less glare/reflections/easier to read the Dial. Your New 6139 Crystal is superior in every way - Just Beautiful. Once I am back in Thailand I might buy a SK crystal to install in another 6139 just to compare... but why waste the time and money on SK

Kyle"



Once again, Thank you Kyle for the opportunity to use one of my New Crystals in your Sunrise Speedtimer and for sharing your thoughts on my New Reproduction 330W18GN00 Crystal.

If it's good enough for your Sunrise, It's good enough for me..........



In conclusion, What's the best crystal in this review? Why the Original of course! What's the best alternative when an original isn't available? Well, That's for you to decide now that you have the Facts!


Bob's your Uncle........:)

 

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Great stuff.

Your commitment to our obsession is truly appreciated.

I have just started thinking about 6139 crystals as I have a bunch of these in the pipeline that will be rebuilt once I'm confident enough to work on the movement.

So where to now with this project?
 

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Awesome write up. Great looking product too.

I’ve had a fair few people send me spencer Klein crystals and I’ve found the same as your pics suggest, they distort the chapter ring the worst out of the lot. Not slating them but his description of them on vids are a bit keen when he’s described them as identical to original.


Only thing I would disagree with is the plexi comment in regards to design, the ones I have in mine are the same shape/fit/design as original but just plastic. Not really sure why they get so much hate when Seiko themselves used the material in a lot of watches and even an old Rolex dive watch uses plastic. Seems to be a hatred for the material like it’s going to implode on us or something.

I’ve found it preferable to use than any other mineral replica from a visual POV and the closest/sharpest and least distorting replica (so far). They fit perfectly and if you scratch them you can easily polish them. It sounds kind of counterintuitive as people always expect plastic to be the rounded, soft one but they look so sharp.

Spencer klein crystal left, acrylic right




Not sure why his are so distorted as the diver crystals people have sent me don’t look like it.


Granted I’d rather have an original or by the looks of things you may have the market now sewn up but they served a purpose for me and I’ve been using them years without issue and until now the best looking. I’ve also run them through the pressure tester without issue.


It’s another thing that amazes me about Seiko, just how incredible the details were 50 years ago. All the crystals are so amazingly well made and crisp, you’d think we’d have nailed the replicas years ago.

Are you selling them somewhere? You May be able to retire soon hehe
 

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Comprehensive Review Indeed! Thank you Tom for the detailed analysis. Your new offering looks terrific. I'm in for several !

There is another repro out there, it is from an ebay seller "watchpartusa". Here are a few photos of the crystal mounted on a 1973 Pogue and including his listing photos combined into a single photo.

While suitable I observe it has a bit more rounded profile where the bevel meets the slightly domed top with this AM offering. The dome appears to be somewhat between a genuine early domed style and later "flat top".
Later note: John (Vette Enthusiast) says in Post #11 below " My biggest complaint with many of the AM crystals out there is the rounded edge appearance as the crystal transitions from the beveled edge to the top surface which does not match the OE crystals from Seiko".

They are frosted on the vertical part of the bevel I try to show that best I can Now that we are getting down into the minutia, I notice it does exhibit a bit from the edge distortion issue. I personally prefer them over the Sternkreuz, partly due to price but this thread makes me realize they fall short to the SK in some areas.

Tom any sort of price premium that yours will command will be well worth any extra money. Put me in for a few !
 

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Great research comparison and what an undertaking into your product, Tom!

Looking forward to hearing more, and whether you’re going to explore other popular reference crystals?


Sent from my iPhone using Tapatalk
 

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Tom, congrats on launching your crystal line for 6139-600X. I know you put a lot of effort into its development and it shows in your write-up. I learned a lot so thank you. My biggest complaint with many of the AM crystals out there is the rounded edge appearance as the crystal transitions from the beveled edge to the top surface which does not match the OE crystals from Seiko. The side profile of your crystal looks dead on. Well done. I look forward to using your crystals on upcoming restoration projects.
 

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Wow Tom, that was an exceptional analysis. As a technical researcher and (adjunct) university professor I’m a stickler for how someone conveys technical information. This was just really, really good work no matter whose crystal someone may want. I look forward to seeing how your crystal looks on my Resist gold dial when you get it in queue.


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Discussion Starter #13 (Edited)
Thanks guys! I appreciate your comments!

A lot of work went into this project and my thanks goes out to my independent source who did the extensive testing on his end. He had access to the equipment which is out of reach for me at the moment. My thanks also goes out to another very generous member who offered to help fund this project if need be. In the end I was able to fund it myself but I was Truly appreciative of his generosity!

My order has shipped and I should have 100 crystals on hand in two or three days. If all goes well I'll be moving forward with other reproduction crystals. As always, Time will Tell.........:)
 

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Thanks guys! I appreciate your comments!

A lot of work went into this project and my thanks goes out to my independent source who did the extensive testing on his end. He had access to the equipment which is out of reach for me at the moment. My thanks also goes out to another very generous member who offered to help fund this project if need be. In the end I was able to fund it myself but I was Truly appreciative of his generosity!

My order has shipped and I should have 100 crystals on hand in two or three days. If all goes well I'll be moving forward with other reproduction crystals. As always, Time will Tell.........:)
Any idea of price Tom ?
 

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My word, that was a superb and detailed review, I learned a lot from it so thank you. I’ll also be joining the sales queue for a few if I may...


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Awesome comprehensive review! I recently purchased a 330W18GN from the competition and to be honest I was expecting something closer to original.

Any plans on doing the 6105-8xxx diver crystals?
 

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Superb work Tom and never too "persnickety" as far as I'm concerned. Your commitment to this particular model is exemplary and will leave an indelible legacy
 

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Discussion Starter #19
Any idea of price Tom ?

That's a good question John. Originally I was quoted a certain price for the reproduction crystal. After it was all said + done it wound up costing a bit more in order to meet my stringent requirements.

I'm thinking $35 + shipping per crystal as an introductory offer which will also include a crystal gasket. As time goes on I may need to raise that to $37.50.
If everything goes as planned, the majority of proceeds will be reinvested to fund my next crystal project.
 

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Discussion Starter #20
Awesome comprehensive review! I recently purchased a 330W18GN from the competition and to be honest I was expecting something closer to original.

Any plans on doing the 6105-8xxx diver crystals?

Time will Tell............;)
 
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