About the Green Crystal in the Milgauss...

[Lol-x]

We look at our watches every day, but we rarely consider the origins of what we are looking through i.e. the sapphire crystal.

The sapphire crystal is an artificial (“synthetic”) man made material that is ‘grown’ over a period of days or weeks.

The growing process is even more complex in the case of the Green Milgauss Crystal.
Corundum is the mineralogical name for the naturally occurring crystalline form of aluminium oxide (sapphire).

The chemical formula for the Synthetic Green Sapphire is Co3+ - Al2O3. In other words synthetic green sapphire is made from Copper and Aluminium Oxide, the latter being the main product of bauxite the principal ore of aluminium.

The production of synthetic sapphire crystals can occur by one of several processes: melt growth, solution growth, or extremely high-temperature, high-pressure growth.

The 4 well known methods of sapphire production are:
1. The Verneuil flame-fusion process
2. The Bridgman-Stockbarge process
3. The Czochralski method
4. The Hydrothermal method

It is not precisely known which method Rolex uses to produce their sapphire crystals, but rumour has it that Rolex uses the Hydrothermal method of producing the green sapphire crystals.

The Hydrothermal method is based on the transformation of melting crashed sapphires and deposit of solution around the beryl seed in a hydrothermal environment. The crashed low grade sapphires, known as nutrient, are melted along with the color inducing chemicals (copper is used for obtaining a green tint). The seed, being a larger and more solid element in the process, attracts smaller particles of the same origin and the growth process begins, depositing layer upon layer on itself. This is the reason for undulated growth lines in hydrothermally grown gems. The process takes around four weeks. If the process is slowed down, the “layers” are deposited at a slower rate, resulting in growth lines being less defined and more difficult to detect.

The process starts by gradually heating the autoclave. Subsequent rise in temperature leads to rise in pressure, as a result of liquid expansion inside the inner vessel. Once the temperature rises to about 600°C and pressure is around 800 PSI, the process reaches an ultimate equilibrium and a melt process begins. Smaller particles are attracted by the larger element, the seed, hence starting the growth process.

http://tairus.com/index_files/emerald.htm

The hydrothermal synthetic sapphire 'growth' process is similar to Synthetic Emerald production process.
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Synthetic sapphire ranks a 9 on the Mohs Scale, this means that one needs to avoid exposure to diamond jewellery, and avoid striking ones watches against artificial stone and simulated stone surfaces. Such surfaces can often contain materials including silicon carbide, which, like diamond, are harder than sapphire and thus capable of causing scratches.

The slow run out of the green crystal milgauss (and the higher cost than the clear crystal models) may well be explained by the complex process involved in the growth of the green crystals. The addition of copper to the process to obtain precisely the right amount of green tint, and the precise pressures and temperatures to yield a perfect product are liable to failures occurring in the ‘growth’ process.

http://www.rolexforums.com/attachment.php?attachmentid=10032&stc=1&d=1188742012

[2careless]

Probably I'll get slammed hard on this... Why are people so adament about that green crystal? Drink some beer and you can see your watch looking green through the beer bottle... :cheers::lol:

[marshallr47]

Good info. Very interesting. Thanks for sharing.

[DaveInLA]

Personally, I think the Milgauss with the green rim is the best looking watch I've ever seen.

[Trurolexer]

Probably I'll get slammed hard on this... Why are people so adament about that green crystal? Drink some beer and you can see your watch looking green through the beer bottle... :cheers::lol:
That's what I'm thinking too, Kai. lol!!!
BTW nice info, Steve.

[mic6]

I heard that the green was not a plain coating on the crystal but natural ...who knows :thinking:

[BiG JeEzY]

Thank you for sharing Steve! That was explained so well and was very educating!! I always am fascinated by Rolex Sapphire crystals and how they are cut so well, perfectly flat. It creates a shine that is very beautiful in my opinion.

[toph]

great info.
:cheers:

[docnagel]

Super explaination. Thank you!!

[youngr]

really enjoyed reading that thanks

[swatty]

Very interesting , Thanks :thumbsup:

[Andad]

Hi Steve,


Excellent information.

I will now enjoy wearing my GV even more. :thumbsup::chuckle:

[Luminor]

all i know is this

[speicher1]

Great thread! Ok question. Is the green crystal purely aesthetic? Or does it have some practical purpose/advantage over the regular crystal?

[OYSTERMANN]

What a fascinating post, Steve - amazing information in there:thumbsup:.

[unclesallie]

Steve: AMAZING. I had no idea.
Thanks!:thumbsup:
best,
dan

[oneillba]

Steve, thanks for the information. I had no idea that the crystals were man made. I thought they were mined, cut and polished. You have given me my Bo fix for the day.

[Trainer]

Great thread!* Ok question.* Is the green crystal purely aesthetic?* Or does it have some practical purpose/advantage over the regular crystal?Good Question!Does this crystal privide a greater resistancto the effects of magnetism?

Tempus Fugit,
Trainer

[Andad]

Oh, sorry Steve, did you want a few more pix.........?

[ROLEX MAN]

Thanks steve excellent!

[Lol-x]

The green crystal is purely an aesthetic feature of the Milgauss GV. The tint is very slight and can really only be observed on the edge of the crystal.
Thanks Eddie I love seeing your Milgauss GV, it is still the only GV I have ever seen in person :banghead: :banghead: :chuckle: :chuckle:
After the crystal has been grown, it must then be cut and finished to exacting standards and so this all adds to the cost and time to make this model. :cheers:

[redshirt1957]

Usually you have to pay for that type of information.:thumbsup: Very well written.:cheers:

[Texsubmariner]

I just wish the Milgauss has a date function, then it would be a perfect watch!

[Lol-x]

Yes, if the Milgauss had a date it would be a very useful addition, but alas we do not dictate the terms :crying:

[Tools]

Great stuff..

This should be posted over in the Milgauss reference section too..

[docnagel]

I just wish the Milgauss has a date function, then it would be a perfect watch!

But that would probably mean a cyclops which may detract from the Green tint in the crystal.

[Leighton]

I just wish the Milgauss has a date function, then it would be a perfect watch!

x2!

Thanks Steve. Great info! :thumbsup: :cheers:

[Beef]

Thanks, Steve. Now I know why I'm still waiting.....

[kilroy]

http://img.photobucket.com/albums/v176/ron92037/IMG_1003.jpg

[jasonbellevue]

Interesting info, thanks for sharing. :thumbsup: :cheers:

[CPCC]

Nice job, thanks

[MAXI DIAL]

I love my GV more and more now. Thanks Lol-x

[Felly Jr.]

http://img.photobucket.com/albums/v176/ron92037/IMG_1003.jpg

Yes, the green edge............

[ricnas1]

thks steve for the info...

i spent quite sometime trying to look for this very same info on the net but came out naught.....

[ricnas1]

I just wish the Milgauss has a date function, then it would be a perfect watch!

i cldnt agree more... :thumbsup:

i reckon it doesnt even need the cyclops so as to keep the clean look of the watch... i'd be happy with just that date function....

[2careless]

I'm uncertain that Milgauss can do a date. Think about the loss of EMI shielding on the date display. By having the "gap" in the date display, there maybe leaks of EMI that can affect the shielding rating. Just food for thought. Any real Elec Engr here?

[jac67]

Thanks Steve, great info. :thumbsup:

Man, you've obviously got too much time on your hands. :chuckle:


John.

[Lol-x]

Thanks Steve, great info. :thumbsup:

Man, you've obviously got too much time on your hands. :chuckle:


John.
Not really John, it did take some time to put the information together, but I worked on it over several days. I just hope the information was interesting and worthwhile.
Now I'm in big trouble at work, so that is what I must now work on. :crying:
:cheers:

[sherwin]

i would be guessing the the majority of people wearing the milgauss would not even work in environments that had high magnetic fields. maybe launch two versions, but the cost would probably be prohibitive

[PA6-541]

Interesting info on the green crystal. In the formula Co3+ Al2O3, how do you know that the Co symbol stands for Copper? When I studied chemistry, Co stood for Cobalt, and Cu stood for Copper.

[The Mole]

I would also add the following to the process,

When synthetic sapphire is manufactured the end result is a "Boulle", which is the synthetic sapphire in a shape that resembles a roll of cookie dough. Almost all watch manufactures cut this boulle perpendicular, along sapphires softest axis to maximize yield.

Rolex cuts the boulle along its hardest axis (roughly diagonally through the boulle), facing the hardest surface "out" to insure additional strength and scratch-resistance....Maximizing waste to maximize quality. Synthetic sapphire cut this way is exponentially harder to polish.

:cheers:

[DeepSeaWatches]

Great info, thanks for sharing that. :)

All I know is I never grow tired of looking at that green crystal. It definitely "scratches a different itch" than any other watch I've ever owned...

[bodybump]

very good point steve....i think its just the uniqueness of the watch..it applies also to other stuff...i dont know why people love stainless steel when TT really gives a very good elegance on the watch (no offense guys) i own a ss too..the milgauss gv IMO is one of the best watch ive seen too...its the only Rolex that has a different crytal on it we have seen all kinds of rolex and sports models but if you put the GV on a sports model watch..the GV will be most to talk at...with the exception of the vintage...if Rolex came out with a red crystal im sure this one will be a major hit too..

[SS Oyster]

I love reading about these incredible details ... another reason to love Rolex. Everything is done IN HOUSE!

[Lol-x]

Interesting info on the green crystal. In the formula Co3+ Al2O3, how do you know that the Co symbol stands for Copper? When I studied chemistry, Co stood for Cobalt, and Cu stood for Copper.

I think you may have a very valid point there. I have heard of cobalt green having been used as a pigment, so maybe cobalt is used rather than copper to obtain the green tint to the crystal.

I would be interested if anyone knew whether cobalt is used as a green tinting agent. :thinking: :agree:

[Z-Sub]

One of my favorite pieces:thumbsup:

[JimC]

Wow... Nice thread with lots of good information. Guess I "need" a GV now. :P

[DanP]

THANK YOU Steve. Very thorough!:clap::thumbsup::thumbsup: Gonna get mine in January:dude:

[wuzzzer]

I'm uncertain that Milgauss can do a date. Think about the loss of EMI shielding on the date display. By having the "gap" in the date display, there maybe leaks of EMI that can affect the shielding rating. Just food for thought. Any real Elec Engr here?

That is exactly why Rolex did not put a date window on the Milgauss. :thumbsup:

[stevemulholland3]

wait a second,the green is not painted on??

[Watch Fan]

Very interresting. Thanks for the info, it makes me appreciate my GV even more!

[tsmack]

Few Shots of the GV

[ttannert]

So, is there any truth to the rumors that Rolex is having problems with the manufacturing process for the GV? :thinking: Or was that all just hype?

[Bisquitlips]

I wondered about this very thing! Thanks for the excellent write up!

[MAINEZX10]

The green crystal is purely an aesthetic feature of the Milgauss GV. The tint is very slight and can really only be observed on the edge of the crystal.
Thanks Eddie I love seeing your Milgauss GV, it is still the only GV I have ever seen in person :banghead: :banghead: :chuckle: :chuckle:
After the crystal has been grown, it must then be cut and finished to exacting standards and so this all adds to the cost and time to make this model. :cheers:

I thought you had one. GREAT POST!!

[shedlock2000]

DOH!

Yesterday, i contacted JJ (he reads to much) to find out if the colour was a gimick or purposefull. I wish i had found this thread, but was searching for mill, and not crystal!

Thanks for the great thread and information Steve (you can now be promoted to a god!) I was very interested in the production of this crystal, and comments on the date function of the watch (loss of anti-magnetism) and such. I am shortly to make a deal on a GMT II, but considering a Millgauss before i do, as i am likely to be heading into school to study medicine (apparently the mill would be handy!)

I love the green edge, and think a blue edge would look sharp on a sub or a GMT SS

Great photos too of the Mill.

[oztimelord]

Excellent post you learn something new everyday:dummy::rofl:. It also highlights how much work goes on behind the scenes to make a Rolex truly great. :thumbsup:

[jas55]

I love to read about the construction and materials that make up a Rolex, well done:)

[Philippe]

Very interesting information. Goes to show the the rumors that Rolex is havign trouble sourcing the glass are nothing to worry about. If they control the process, I am sure they will be able to fix it.

[Davvan]

Supergreeeeeen :thumbsup:

[vapalux]

Hi Steve

Thanks for the fascinating info. Very interesting and a great help:thumbsup:

Si

[Dubai]

Great Info , thanks for sharing !

[2th Dr]

Interesting and informative. Thank you!

[aaafamily]

super detail explaination. great. .thanks

[eric23]

Great info and nice photos!!