# Seiko Glass - Hardex To Saphire ?



## nigelw (Jul 28, 2010)

Hi

I have a Seiko 5 that is approx 16 years old & was a gift from my parents.

Is it possible to replace the hardex crystal with a saphire (curved or flat) ?

The reference on the case back is 7009-3100 A1.

Thanks in advance for any help.

Nigel.


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## SEIKO7A38 (Feb 12, 2009)

nigelw said:


> Is it possible to replace the hardex crystal with a sapphire (curved or flat) ?
> 
> The reference on the case back is 7009-3100 A1.


Looks something like this I presume ? 










Jules Borel list Seiko p/n 290W49LN00 as the original fitment - referencing p/n 290W34GN00 as a substitute.

So it's just a flat round 29.00mm Ã˜ crystal that you need. :smartass: Or is it possibly slightly domed ? 

Not sure of the thickness either (you can't tell that from the Seiko part number) ....

Unfortunately, Cousins UK don't stock either of them - see: http://www.cousinsuk.com/searchresults.aspx?searchtext=SEIKO_290W

But what I'd be inclined to do is fit a Sternkreuz hardened mineral glass 29.00mm Ã˜ crystal ....

Something like Sternkreuz p/n MS290 (1.00mm thick) or MSM290 (1.5mm thick), costing a mere Â£1.70.

The equivalent Sternkreuz flat round sapphire crystal, p/n MSR290 (1.4mm thick) will cost you Â£19.45.

Sternkreuz domed sapphire crystals come in 0.90mm thickness, and p/n SRD290 would cost you Â£49.50 ! 

Alternatively, there's Cousins' own brand 29.00mm Ã˜ x 1.0mm thick sapphire, p/n FS100CMH290 at Â£7.74.


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## bry1975 (Feb 6, 2004)

IMO Cousins do take the Smichael with their domed sapphire prices and some of those cheapy minerals never clean up properly!


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## Guest (Jul 29, 2010)

If you end up getting to choose between domed or flat, I'd definitely go for flat.

Domed is stronger, and makes watches look more "shiny" as jewellery ...but flat just seems to be clearer when you want to tell the time.


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## SEIKO7A38 (Feb 12, 2009)

Om_nom_nom_Watches! said:


> If you end up getting to choose between domed or flat, I'd definitely go for flat.
> 
> Domed is stronger, and makes watches look more "shiny" as jewellery ...but flat just seems to be clearer when you want to tell the time.


Domed with a flat bottom also magnifies, slightly. 

As opposed to 'curved' (presumably meaning bi-convex), as per the OP:



nigelw said:


> Is it possible to replace the hardex crystal with a sapphire (*curved* or flat) ?


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## SEIKO7A38 (Feb 12, 2009)

bry1975 said:


> IMO Cousins do take the Smichael with their domed sapphire prices ....


My bad there, Bry.









Where I wrote:



SEIKO7A38Fan said:


> Alternatively, there's Cousins' own brand 29.00mm Ã˜ x 1.0mm thick sapphire, p/n FS100CMH290 at Â£7.74.


Cousins' p/n FS100CMH290 is a *flat round* 29.00mm Ã˜ x 1.0mm thick sapphire.

They don't do an 'own brand' domed sapphire crystal - only the Sternkreuz SRD range.


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## nigelw (Jul 28, 2010)

Thanks for the replies.

The watch pictured is similar to mine - mine has a silver dial and stick shape hands.

I will have a look at the crystals listed. - I really wanted saphire as I have never had a watch with saphire crystal before. But the mineral has held up well enough over the years.

I did not realise about the magnification of a domed crystal - I have an Oris with plexi glass and I just imagined it like that - but I guess saphire is a totally different material.

With regards to the crystal - does the thickness matter for fitting ? Or is the only difference how high it sits over the bezel ? - My watch sits about level but I have seen Rolex flat saphires that sit 2mm or so proud of the case & look nice.

Thanks again for any help.

Nigel.


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## SEIKO7A38 (Feb 12, 2009)

nigelw said:


> With regards to the crystal - does the thickness matter for fitting ?
> 
> Or is the only difference how high it sits over the bezel ?
> 
> My watch sits about level but I have seen Rolex flat saphires that sit 2mm or so proud of the case & look nice.


I tend to replace like with like - as close as I can get to the original thickness, say +/- 0.1mm.

One (or two) downsides of fitting a crystal, which when properly seated, sits proud of a bezel ....

particularly if it has just a plain ground edge, rather than say a polished bevelled top edge,

(such as you might find on a crystal designed for use with a 'Diver's rotating bezel) is that ....

it might be unsightly, and obviously would be more vulnerable to chipping around the edge.


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## nigelw (Jul 28, 2010)

That makes sense - Thanks.

Nigel.


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## nigelw (Jul 28, 2010)

Hi

Just an update.

I bought a crystal press and the 29mm cousins own saphire and have installed it myself - cracked the old crystal getting it out but hope to get better with practice.

The flat saphire looks good - still wondering about the domed - but the cost seems very high.

Thank you to everyone who gave me advice.

Nigel.


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## Roger the Dodger (Oct 5, 2009)

nigelw said:


> Hi
> 
> Just an update.
> 
> ...


Any pics, Nige?


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## ralphy (Nov 24, 2008)

I'm undergoing a trasformation from hardlex to sapphire at the moment on a Seiko too. It's in the hands of Paul (Silver Hawk) and he mentioned the domed sapphire (which I sourced from Harold Yobokies) may sit lower, so we'll see soon.

As you can see, the Hardlex was rather overdue for replacement:




























Bit shocked at Cousins price for a replacement bezel insert, though: it is Â£43.95....so with VAT and shipping, assume about Â£55 - much more than the one for my Sub. :shocking:

R


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