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Rolex GMT 1675 crystal insights (tropical from clarks, truedome, lobtime) and bezel discussions

mew

Active Member
18/12/15
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Germany
Hey guys,

like many of you I took building a true 1675 very serious and have spend way too many times sourcing parts which are gen spec (I do own a gen 1675 gilt from 1964).

I started my journey with a cheap Milk case set - I would probably not go that route again. The case is okish for the price, but the bezel assembly doesnt fit inserts without sanding them down and the bezel looks pretty bad overall (wrongly polished, too high etc). I did order a 1675 bezel from the german company ernst westphal which is 10x better. Below are some pictures of both bezels (the one installed is the good one from ernst westphal).

Now when it came to crystals I started out with a Clarks t38 (approx 30€). This one proved to be a problem with the 2836 gmt pinion height and the second hand would drag against the crystal - just not enough clearance. This one did look the best out of the cheap options (!) It is mounted on the watch in the last picture but had to be removed for clearance issues.

I then tried a lobtime crystal which is veeery highly domed and doesnt look too good. I ended up purchasing a truedome 38 and the difference is literally night and day. But I guess that's what you get for a crystal that costs 300$. The clarity is insane. Build quality absolutely top notch. It will go onto my gen 1675, but for my next build I would definitely get one again. They are just too good to pass up.

So in essense best crystal -> T38 TrueDome (expensive), then T38 Clarks (cheap but have to watch for correct pinion height clearance).

Bezels -> Ernst westphal is top notch. Unfortunately it doesnt come as full assembly so if anyone knows where to find a good gen spec retainer ring, then let me know.


I know the pictures can be a bit confusing since there are a total of 4 crystals shown (T119 EW, T38 Clarks mounted on last picture, T38 tobtime - mounted right now, super high dome, and T38 TrueDome, shown on the very right when comparing the 3 crystals with highest clarity)




 

Kingseiko

You're Saying I Can Sell?
27/4/19
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Would you say Clark’s 25-116 clarity would be on par of their t38 Crystal ?
 

kilowattore

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True dome crystal looks very clear but 300 USD.... Whoa
 

automatico

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5/10/11
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The last genuine 25-116 (case ref 1675) crystals I bought were around $28 each iirc.
Fyi...in 1995 I paid $17.50 for genuine Cyclops types and Tropics were $15.50 from DRS Supply in NYC...before RWC started closing the parts supply down.

I've tried many brands of acrylic crystals and a few of the things I have learned are:
1...Many crystals do not fit correctly, no matter where they came from.
2...Some crystals are a whole lot better than others.
3...Quality can change from one order to the next, even from the same supplier.
4...When you find a crystal that fits, quickly order a few more. Hopefully they will be the same.
5...Price really does not have a whole lot to do with what you get.
6...Genuine crystals are somewhat overrated. Imho.
7...Old 'genuine' crystals may not fit properly and may crack easily.
8...A good crystal press and press cups are a necessity.
9... Metal press cups are better than flimsy plastic cups.
10...Fitting a bezel over an acrylic crystal takes practice.
11...Invest in a quality digital caliper.

What brands of rolex type crystals have I had good luck with lately besides genuine?
In no particular order...
1...Sternkreuz.
2...StarTime.
3...Clark's.
4...GS.

Measure the ID of the bezel in a few different spots (write it down), measure the OD of the crystal skirt mounted on the case neck in 3 or 4 places (write it down).
Usually, .2 to .3mm difference in the bezel ID and crystal OD is Ok, depending on how flexible the crystal material is.
The crystal OD may be larger close to the case where it fits over the case neck than it is at the top edge. Allow for it...if a crystal is 28.0mm at the top and 28.5 or so at the bottom, you may have trouble. Then again, you may not, it depends. This is where trial error comes in...along with cheap crystals.

Notes:
1...if an inner bezel ring on a 5512/5513/1680 etc. is too tight when pressing it over the crystal, it may make the rotating bezel sticky or hard to turn because it has been slightly expanded.
2...Solid gold bezels may break if they are too tight.

Everyone cheats...I have used a tiny amount of Dawn detergent as a lubricant on the ID of bezels to prevent 'chattering' and help prevent getting the press cup and/or bezel ring out of level. Be careful if you try this because Dawn etc. travels like water and can get on a dial if too much is used. I will deny I ever said this. Ha!
After installing a few crystals, you will develop a 'feel' for a proper fit.

Q...How many rolex type acrylic crystals have I installed?
A...A few hundred, mostly genuine crystals.
Q...What type of crystal press do I use?
A...An old cast iron and steel BB Crystal Co, model with aluminum cups.
Q...How many crystals have I cracked?
A...More than I am proud of.
 

easy_beaching

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300 usd for a true dome... ouch
personally, i prefer having the cyclops, the 1675 just looks weird without it.

clark is good enough for me, got a couple spares too lol, just in case :p
Clark's mag is hit or miss though. The height is really the tough variable with cyclops. Got a shot of yours face on?
 

easy_beaching

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I had a gen plexi on my 1675 and it cracked, so rather than spend $250+ to replace it, I thought I would try Clarks. When I installed it I immediately noticed there was a mag problem - it's very slight, but after looking at a gen mag for years it was substantial to me. Below is a comparison between your watch (right) and Ismael's (left) which has a gen plexi. You can see the mag difference and it appears subtle in the pics, but it definitely stands out to me. I am now contemplating taking the plunge to go gen again, but the cracking susceptibility is a big turn off.
 

notyourbusinessmate

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I had a gen plexi on my 1675 and it cracked, so rather than spend $250+ to replace it, I thought I would try Clarks. When I installed it I immediately noticed there was a mag problem - it's very slight, but after looking at a gen mag for years it was substantial to me. Below is a comparison between your watch (right) and Ismael's (left) which has a gen plexi. You can see the mag difference and it appears subtle in the pics, but it definitely stands out to me. I am now contemplating taking the plunge to go gen again, but the cracking susceptibility is a big turn off.
I agree on this. Especially for the 1680s, I haven’t seen a rep Plexi so far having the same level of magnification than a Gen. If someone can recommend a cheaper one, pls let me know.
 
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MJH89

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That's not great news about the Clark t38 nsot clearing the pinion, I'm now slightly worried that I will have caused Tripdog a pain in the backside having ordered one for him to fit for my build.