Tom Posted May 12, 2008 Report Share Posted May 12, 2008 I want to send some of my crystals to be AR coated. On the dealers site they state that my watches are "sapphire", but is this true or are they all mineral glass? Anyone know an easy way to tell. Apparently there is no point in AR coating mineral glass, so if I sent them unknowingly it would be a waste of money. Quote Link to comment Share on other sites More sharing options...
Nanuq Posted May 12, 2008 Report Share Posted May 12, 2008 I know you're supposed to place one drop of water on the center of the crystal. If it remains a circle then it's a sapphire. If it spreads out it's mineral glass. (or was it the other way around?) Quote Link to comment Share on other sites More sharing options...
Ylfig Posted May 12, 2008 Report Share Posted May 12, 2008 No Nanuq, you Quote Link to comment Share on other sites More sharing options...
peepshow Posted May 12, 2008 Report Share Posted May 12, 2008 I don't know how much stock I put in the "water drop" test. I tried it on an old-school, Seagull powered PAM212 rep that I had and the water stayed beaded. AFAIK, no 212 reps were ever offered with sapphire crystals and certainly not the ones with the cheapest of all movements. Having said that, why would AR coating be a waste of money on a mineral crystal? I'm not super-delicate with my watches, and I've never scratched a mineral crystal.... Quote Link to comment Share on other sites More sharing options...
hooky Posted May 12, 2008 Report Share Posted May 12, 2008 I always use a diamond tester, an electronic device bought from Ebay. It never fooled me. Just my 2 cents. Quote Link to comment Share on other sites More sharing options...
mjmills Posted May 12, 2008 Report Share Posted May 12, 2008 very simple, if it is domed tilt it up and look at the numbers, if they distorn then it is mineral, if they stay clean then its sapphire, that is why sapphire is better! Quote Link to comment Share on other sites More sharing options...
andreww Posted May 12, 2008 Report Share Posted May 12, 2008 very simple, if it is domed tilt it up and look at the numbers, if they distorn then it is mineral, if they stay clean then its sapphire, that is why sapphire is better! Another misconception. If you look at the Breitling Avenger reps which are sapphire, there is a noticeable distortion when viewed at an angle. The asian SFSO however, which is mineral is clear as any crystal I've seen. Distortion is more a factor of the shape and thickness of the crystal, than the material from which it is made. Quote Link to comment Share on other sites More sharing options...
Pix Posted May 12, 2008 Report Share Posted May 12, 2008 I rely on the water drop test, which has been pretty successful untill now, in comparison with what was advertized. Except for my Asian SFSO, for which I still can't define if it's mineral or sapphire. As for coating mineral, I did it. Tell you the results hopefully in the coming days. Quote Link to comment Share on other sites More sharing options...
surpur Posted May 12, 2008 Report Share Posted May 12, 2008 Another misconception. If you look at the Breitling Avenger reps which are sapphire, there is a noticeable distortion when viewed at an angle. The asian SFSO however, which is mineral is clear as any crystal I've seen. Distortion is more a factor of the shape and thickness of the crystal, than the material from which it is made. I have to agree somewhat with Andrew. If I get a watch with a curved crystal that distorts the view I buy a $3 curved mineral crystal at my local watch supply house and its clear as day. Obviously they are often using the cheapest glass they can find on the reps. That said - the same watch supply dealer would charge me $30 for sapphire and for 10 times the price you really cannot see the differnce by eye. This huge price differnce makes me wonder how many 'Sapphire' crystals are really sapphire?? Considering the low price of the reps. I am not wondering enough to invest in a diamond tester, but maybe Hooky could give us a rundown what he found out about how many are real sapphire. That would be great - Thanks! Quote Link to comment Share on other sites More sharing options...
sssurfer Posted May 12, 2008 Report Share Posted May 12, 2008 Tom, there have been a lot of threads about it, I too posted my thoughts, if you do a search you should find them. I'll try and make a summary as well: The cheap tests (waterdrop, fingernail, color, subjective temperature, distortion, etc), they all are not conclusive if taken individually. But if they all point to a same result, then they tell something. The electronic tool(s) mentioned by hooky and described in one of my threads are very reliable also in my experience. AR coating a glass crystal is excellent, as in one single step you get the crystal AR coated and more scratch-resistant than before. The problem is that the AR makers calibrate their AR coating treatment on the median refractive index of the batch that is undergoing the treatment. So, if it is a batch especially made of sapphire crystals, your glass crystal is not going to get the best possible AR coating related with its refractive index. But if you can start a batch of glass crystals you should get an excellent AR, at par with sapphire. Quote Link to comment Share on other sites More sharing options...
hooky Posted May 12, 2008 Report Share Posted May 12, 2008 I got the diamond tester, because i deal with many replica's, also for sale. And i need to know what i am selling and also what i am paying for. The tester always worked so far. Some watches were marketed as being sapphire, but actually were not. For instance the PAM253 and a BR02. Sometimes the dealer markets its watch as being 'synthetic sapphire'. Whatever that is. And some as 'real sapphire'. For what i know all sapphire made for watches is synthetic made. And something being marketed as 'synthetic sapphire' sometimes actually is mineral glass. Als i found something on some Hublot Big Bang watches. From the normal 'old' factory, the one with 28.8k movement, the HBB Lite: The front is sapphire, the back plain mineral. From the new factory with 21.6k movement, the Lite version with AR has both front and back with sapphire. .... Most expensive high end replica's which are marketed as sapphire also have sapphire. The PAM253 was an exception, because the domed glass is quite unique and not used on other models. That is why probebly they did not make that anymore. Cheers, J. Quote Link to comment Share on other sites More sharing options...
Tom Posted May 12, 2008 Author Report Share Posted May 12, 2008 Having said that, why would AR coating be a waste of money on a mineral crystal? I'm not super-delicate with my watches, and I've never scratched a mineral crystal.... I had a quick conversation with Jakub (K2222) who said that AR isn't that visable on mineral glass so it's not really worth it. Quote Link to comment Share on other sites More sharing options...
Pix Posted May 12, 2008 Report Share Posted May 12, 2008 I always use a diamond tester, an electronic device bought from Ebay. It never fooled me. Just my 2 cents. I checked for the tool which seems affordable. But it's say to recognize diamonds. Can you explain more on the indications given ? Are there various gems which are analyzed ? Thx for any comment. Quote Link to comment Share on other sites More sharing options...
hooky Posted May 12, 2008 Report Share Posted May 12, 2008 I checked for the tool which seems affordable. But it's say to recognize diamonds. Can you explain more on the indications given ? Are there various gems which are analyzed ? Thx for any comment. Works very simple. press the end of the tool on the glass. wait until it beebs. if it beebs it is sapphire. if not, then not. Quote Link to comment Share on other sites More sharing options...
surpur Posted May 12, 2008 Report Share Posted May 12, 2008 Works very simple. press the end of the tool on the glass. wait until it beebs. if it beebs it is sapphire. if not, then not. Ok - I went to a Jeweler I know who has a diamond tester. Turns out that of all my watches only my Sub and Day date Rolies had sapphire, both are high end with ETA movements. Quote Link to comment Share on other sites More sharing options...
Pix Posted May 12, 2008 Report Share Posted May 12, 2008 Works very simple. press the end of the tool on the glass. wait until it beebs. if it beebs it is sapphire. if not, then not. Thx So it's a sapphire tester, not diamond tester ? Sorry for a dumb question. Quote Link to comment Share on other sites More sharing options...
k2222 Posted May 12, 2008 Report Share Posted May 12, 2008 Mineral is different in feel, it is also not that havy as saphire, AR will not be that good and prominent on a mineral, as the method is set up for saphire crystals Quote Link to comment Share on other sites More sharing options...
hooky Posted May 12, 2008 Report Share Posted May 12, 2008 Come on Pix! take a look on Ebay, searching for 'diamond tester'. both sapphire and diamonds are very strong and hard/solid materials. Mineral glass is much softer. So it recognises the sapphire as diamond and the mineral glass as 'no diamond/sapphire' bought mine from: http://stores.ebay.com/tools852 Cheers, J. Quote Link to comment Share on other sites More sharing options...
Pix Posted May 12, 2008 Report Share Posted May 12, 2008 That's what I wished to read Sorry, I prefer to be dumb for a second than being dumb after I paid 40 EUR for a thing that I could not use... I'm going to order that thing, thx for the tip !! Quote Link to comment Share on other sites More sharing options...
surpur Posted May 12, 2008 Report Share Posted May 12, 2008 Come on Pix! take a look on Ebay, searching for 'diamond tester'. both sapphire and diamonds are very strong and hard/solid materials. Mineral glass is much softer. So it recognises the sapphire as diamond and the mineral glass as 'no diamond/sapphire' bought mine from: http://stores.ebay.com/tools852 Cheers, J. Actually it looks for the thermo conductivity of gems. Diamond has a very high and specific conductivity value and those testers are programmed for that number. Sapphire has a very similar value, so on a good tester you can see that. Mineral glass has a very low thermo conductivity, so it is very easy to see the difference. Quote Link to comment Share on other sites More sharing options...
hooky Posted May 12, 2008 Report Share Posted May 12, 2008 Actually it looks for the thermo conductivity of gems. Diamond has a very high and specific conductivity value and those testers are programmed for that number. Sapphire has a very similar value, so on a good tester you can see that. Mineral glass has a very low thermo conductivity, so it is very easy to see the difference. I suspected it was something else than the hardness of the material, since it does not scratch the surface while testing and it also works with electricity. Once i touched the tip of the tester. Ouch!! strong electrical shock.... Just went for the simple explanation haha. Sorry. Thank you for your explanation. J. Quote Link to comment Share on other sites More sharing options...
sssurfer Posted May 12, 2008 Report Share Posted May 12, 2008 http://www.rwg.cc/members/index.php?showtopic=8318 Quote Link to comment Share on other sites More sharing options...
freddy333 Posted May 14, 2008 Report Share Posted May 14, 2008 Anyone know an easy way to tell. Apparently there is no point in AR coating mineral glass, so if I sent them unknowingly it would be a waste of money. 1. Mineral glass (glass) has a green tint when viewed from the side (unless purposely colored during the manufacturing process (like the new Milgauss Anniversary) sapphire appears white or clear). This is probably the easiest way for most people to identify a glass lens. 2. Mineral glass, at room temperature, always feels cool to the touch. Sapphire tends to feel cool as well, but it does not feel as cool relative to (mineral) glass. Quote Link to comment Share on other sites More sharing options...
hooky Posted May 14, 2008 Report Share Posted May 14, 2008 1. Mineral glass (glass) has a green tint when viewed from the side (unless purposely colored during the manufacturing process (like the new Milgauss Anniversary) sapphire appears white or clear). This is probably the easiest way for most people to identify a glass lens. 2. Mineral glass, at room temperature, always feels cool to the touch. Sapphire tends to feel cool as well, but it does not feel as cool relative to (mineral) glass. Totally have to agree with Freddy333 on his 2nd point. Just came back from my watch smith today and he asked me if a certain glass was mineral or sapphire. For that he held the glass to his cheek to feel the temperature. He told me that the conductivity of sapphire is higher, therefore is less cold than mineral glass. I guess his 'testing' method is a fast tell and no need to play around with water drops on top of the glass. And practical for those who don't own a diamond tester. Just my 2 cents. J. Quote Link to comment Share on other sites More sharing options...
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