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#1
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"gem quality"
hi
when people use the phrase "gem quality" to describe gemstones, preferably diamonds in this case, what exactly does that mean - in regards to clarity? SI2+ is gem quality? VS2+ is gem quality? I3+ is gem quality? please explain, thanks! |
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#2
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The term "gem quality" is a qualitative, subjective term, not quantitative.
It is similar to the term "ore", which is determined by the profit or loss if mined and sold at any given time. (If it can't be sold at a profit then it is not ore.) What you might consider as industrial, carving, junk grade, someone else might still use the material as a gemstone. Of course diamond grading comes as close to quantifying the term as humanly possible, (but who knows maybe one day Bort will be fashionable and considered a gem quality material by the folks that are into black "Lawrence" wrote in message ... hi when people use the phrase "gem quality" to describe gemstones, preferably diamonds in this case, what exactly does that mean - in regards to clarity? SI2+ is gem quality? VS2+ is gem quality? I3+ is gem quality? please explain, thanks! |
#3
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"Lawrence" wrote in message ... hi when people use the phrase "gem quality" to describe gemstones, preferably diamonds in this case, what exactly does that mean - in regards to clarity? SI2+ is gem quality? VS2+ is gem quality? I3+ is gem quality? please explain, thanks! iirc, the diamond grading system (well, the GIA at least) goes like this... 1. IF - internally flawless, meaning not inclusions or blemishes of any sort when looking under a 10x microsope/loupe 2. VVS - very very slight inclusions (either 1 or 2) meaning it has minute inclusions that are hard to spot for a seasoned diamond grader under a 10x magnification. 3. VS - very slight (either 1 or 2). Stones that contain minor inclusions that are difficult to fairly easy to see under 10x magnification 4. SI - Slightly Included (either 1 or 2, SI3 is not recognized b/c it's really I1). the inclusions are noticeable and can be detected by a trained grader to see under 10x magnification 5. I - Included (ranges from 1-3). they are obvious inclusions and easy to spot under a 10x magnification by a seasoned/trained grader. Furthermore, sometimes the inclusions be seen without the need of magnification. I've seen some inclusions right off the bat as the stone was placed in front of me. Furthermore, some of the inclusions are so large it effects the overall beauty of the stone. To the best of my knowledge (and I could be wrong) when they say gem quality, it means the overall appearance of the stone - cut, clarity, color and carat. When I buy diamonds, I tend to go for VVS2 or VS1. Yes, it costs a bit more, but it's worth it. CeM |
#4
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On Mon, 30 May 2005 15:18:12 -0700, in ¸õ "CeM"
wrote: iirc, the diamond grading system (well, the GIA at least) goes like this... 1. IF - internally flawless, meaning not inclusions or blemishes of any sort when looking under a 10x microsope/loupe No INTERNAL inclusions or blemishes. The IF grade allows minor surface imperfections, such as tiny nicks or scratches, which could be polished out by a diamond cutter, without significant loss of weight. Some wiggle room there, as the definition of how much weight is considered significant, isn't given. Certain other types of surface defects are allowed too, including small naturals on the girdle, as well as minor internal graining. 2. VVS - very very slight inclusions (either 1 or 2) meaning it has minute inclusions that are hard to spot for a seasoned diamond grader under a 10x magnification. This is sometimes described not as "hard to spot", but "extremely difficult to see". Means about the same, but emphasizes just how minor these inclusions are, especially with the VVS1 grade. 3. VS - very slight (either 1 or 2). Stones that contain minor inclusions that are difficult to fairly easy to see under 10x magnification If they verge into the "fairly easy to see" range, one has to then begin to ask just when it's an SI1 instead. The key word is "minor" inclusions. usually these are at least somewhat difficult to see, at least at first glance. 4. SI - Slightly Included (either 1 or 2, SI3 is not recognized b/c it's really I1). the inclusions are noticeable and can be detected by a trained grader to see under 10x magnification SI2 generally goes all the way to inclusions that are obvious and easy to see, perhaps even quite dominating to the view of the stone, under 10x. The key points are that these should not be visible to the naked eye in the face up position, and cannot be inclusions that significantly affect the durability of the stone (even a not very obvious cleavage, in the wrong place so as to make the stone more fragile or harder to set, usually will make a grader think about assigning an I1 grade or lower. 5. I - Included (ranges from 1-3). they are obvious inclusions and easy to spot under a 10x magnification by a seasoned/trained grader. Furthermore, sometimes the inclusions be seen without the need of magnification. I've seen some inclusions right off the bat as the stone was placed in front of me. Furthermore, some of the inclusions are so large it effects the overall beauty of the stone. I1 is generally the dividing point between when you can see the inclusions to the naked eye or not. If not, and they're not a danger to the stone, it will generally still be an SI2. So the imperfect (I) grades generally have inclusions that ARE visible to the unaided eye, or are severe enough hazards to the stone to warrange downgrading the stone. Mind you, this visibility generally assumes a trained observer, proper lighting, and an unmounted stone. If any of these are not present, the viewer might not see the inclusions in an I1. if the inclusions are actually easy to see with the unaided eye, then generally an I2 applies. And I 3 are those stones where the inclusions are obvious and objectionable to the unaided eye, verging into those stones where you not only wonder how they managed to hold it together to cut the thing, but you wonder why they bothered. These last, the lower end of the I3 grade, start to get to the point where the original term this thread asked about, "gem quality" starts to become an issue, some some of these things hardly deserve the honor of being called gems... Often one sees inexpensive jewelry set with what are euphomistically called "promo grade". Technically they are diamonds. But often are so transluscent and cloudy, that using any sort of clarity grading description is meaningless. To the best of my knowledge (and I could be wrong) when they say gem quality, it means the overall appearance of the stone - cut, clarity, color and carat. "Gem quality" is one of those terms without a precise meaning. It's meaning, like much of the old style gemological terminology, tends to be whatever the speaker wishes it to be at the moment. Useful in general conversation, but not so useful in precisely describing a gem. More of an emotional term, it suggests that a gem is of sufficient quality to be used as a gem, or to be identified as a finer example of a gem. Both these meanings are used, and you'll note they are quite different. An example: A diamond dealer showing you his cut stones may pick out a finer stone and describe it as "real gem quality" or some such, to mean it's better than the average. It's a "real gem" of a stone, he might say... You then know he's really impressed by that stone (and wants perhaps to sell it?) But you know little else without more detail. Meanwhile a lapidary dealer may dig out a nice bit of labroadorite, better than the architectural grade building stone labradorite his store is faced with on the outside, and showing you the colors, explain that this stuff, unlike the building ornamental stone, is gem quality labradorite. This does not then mean that it's the top quality facet grade or anything. Just that it's usable as a gem. Like I said, a highly variable meaning. Unlike the GIA terms, which have a precise definition, which can be referred to by anyone, simply by looking to the organization that came up with the terms and issued a precise definition. That still doesn't mean everyone uses the terms accurately. There are a lot of people in the industry who've not actually obtained their gemological training from GIA itself (either the classes, or the published materials), and some of them sometimes are less than totally accurate in their use of the GIA terms. But one can at least, say that there ARE, at the base of it all, those precise definitions. Peter Rowe (G.G.) |
#5
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"Peter W.. Rowe," wrote in message ... On Mon, 30 May 2005 15:18:12 -0700, in ¸õ "CeM" wrote: iirc, the diamond grading system (well, the GIA at least) goes like this... 1. IF - internally flawless, meaning not inclusions or blemishes of any sort when looking under a 10x microsope/loupe No INTERNAL inclusions or blemishes. The IF grade allows minor surface imperfections, such as tiny nicks or scratches, which could be polished out by a diamond cutter, without significant loss of weight. Some wiggle room there, as the definition of how much weight is considered significant, isn't given. Certain other types of surface defects are allowed too, including small naturals on the girdle, as well as minor internal graining. 2. VVS - very very slight inclusions (either 1 or 2) meaning it has minute inclusions that are hard to spot for a seasoned diamond grader under a 10x magnification. This is sometimes described not as "hard to spot", but "extremely difficult to see". Means about the same, but emphasizes just how minor these inclusions are, especially with the VVS1 grade. 3. VS - very slight (either 1 or 2). Stones that contain minor inclusions that are difficult to fairly easy to see under 10x magnification If they verge into the "fairly easy to see" range, one has to then begin to ask just when it's an SI1 instead. The key word is "minor" inclusions. usually these are at least somewhat difficult to see, at least at first glance. 4. SI - Slightly Included (either 1 or 2, SI3 is not recognized b/c it's really I1). the inclusions are noticeable and can be detected by a trained grader to see under 10x magnification SI2 generally goes all the way to inclusions that are obvious and easy to see, perhaps even quite dominating to the view of the stone, under 10x. The key points are that these should not be visible to the naked eye in the face up position, and cannot be inclusions that significantly affect the durability of the stone (even a not very obvious cleavage, in the wrong place so as to make the stone more fragile or harder to set, usually will make a grader think about assigning an I1 grade or lower. 5. I - Included (ranges from 1-3). they are obvious inclusions and easy to spot under a 10x magnification by a seasoned/trained grader. Furthermore, sometimes the inclusions be seen without the need of magnification. I've seen some inclusions right off the bat as the stone was placed in front of me. Furthermore, some of the inclusions are so large it effects the overall beauty of the stone. I1 is generally the dividing point between when you can see the inclusions to the naked eye or not. If not, and they're not a danger to the stone, it will generally still be an SI2. So the imperfect (I) grades generally have inclusions that ARE visible to the unaided eye, or are severe enough hazards to the stone to warrange downgrading the stone. Mind you, this visibility generally assumes a trained observer, proper lighting, and an unmounted stone. If any of these are not present, the viewer might not see the inclusions in an I1. if the inclusions are actually easy to see with the unaided eye, then generally an I2 applies. And I 3 are those stones where the inclusions are obvious and objectionable to the unaided eye, verging into those stones where you not only wonder how they managed to hold it together to cut the thing, but you wonder why they bothered. These last, the lower end of the I3 grade, start to get to the point where the original term this thread asked about, "gem quality" starts to become an issue, some some of these things hardly deserve the honor of being called gems... Often one sees inexpensive jewelry set with what are euphomistically called "promo grade". Technically they are diamonds. But often are so transluscent and cloudy, that using any sort of clarity grading description is meaningless. To the best of my knowledge (and I could be wrong) when they say gem quality, it means the overall appearance of the stone - cut, clarity, color and carat. "Gem quality" is one of those terms without a precise meaning. It's meaning, like much of the old style gemological terminology, tends to be whatever the speaker wishes it to be at the moment. Useful in general conversation, but not so useful in precisely describing a gem. More of an emotional term, it suggests that a gem is of sufficient quality to be used as a gem, or to be identified as a finer example of a gem. Both these meanings are used, and you'll note they are quite different. An example: A diamond dealer showing you his cut stones may pick out a finer stone and describe it as "real gem quality" or some such, to mean it's better than the average. It's a "real gem" of a stone, he might say... You then know he's really impressed by that stone (and wants perhaps to sell it?) But you know little else without more detail. Meanwhile a lapidary dealer may dig out a nice bit of labroadorite, better than the architectural grade building stone labradorite his store is faced with on the outside, and showing you the colors, explain that this stuff, unlike the building ornamental stone, is gem quality labradorite. This does not then mean that it's the top quality facet grade or anything. Just that it's usable as a gem. Like I said, a highly variable meaning. Unlike the GIA terms, which have a precise definition, which can be referred to by anyone, simply by looking to the organization that came up with the terms and issued a precise definition. That still doesn't mean everyone uses the terms accurately. There are a lot of people in the industry who've not actually obtained their gemological training from GIA itself (either the classes, or the published materials), and some of them sometimes are less than totally accurate in their use of the GIA terms. But one can at least, say that there ARE, at the base of it all, those precise definitions. Peter Rowe (G.G.) I was going by memory from a diamond grading course I took a year ago through a GIA extension class. I haven't graded diamonds professionally - not sure if I could handle so many bright shiny objects in the course of one day. I knew someone would set me straight. Thanks, Peter. CeM |
#6
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well lawerence;
i've or noel have spent about 2 grand to learn about such stuff. but i can't figure out how to post here and keep my non hacking agreement with noel. peter will tell you. andy "Lawrence" wrote in message ... hi when people use the phrase "gem quality" to describe gemstones, preferably diamonds in this case, what exactly does that mean - in regards to clarity? SI2+ is gem quality? VS2+ is gem quality? I3+ is gem quality? please explain, thanks! |
#7
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On Sat, 16 Jul 2005 22:06:48 -0700, in ôõ "Spike"
wrote: well lawerence; i've or noel have spent about 2 grand to learn about such stuff. but i can't figure out how to post here and keep my non hacking agreement with noel. peter will tell you. andy Andy, As mentioned in my email to you, (and here in case you don't for some reason get the email), the above message and your email note leaves me confused. Have you had postings not show up in the group? If so, I can assure you've I've not been blocking or rejecting anything from you. Please contact me via email if you've been having problems posting, and we can try and find a solution. Peter Rowe moderator rec.crafts.jewelry |
#8
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"Peter W.. Rowe," wrote in message ... On Sat, 16 Jul 2005 22:06:48 -0700, in ôõ "Spike" wrote: well lawerence; i've or noel have spent about 2 grand to learn about such stuff. but i can't figure out how to post here and keep my non hacking agreement with noel. peter will tell you. andy Andy, As mentioned in my email to you, (and here in case you don't for some reason get the email), the above message and your email note leaves me confused. Have you had postings not show up in the group? If so, I can assure you've I've not been blocking or rejecting anything from you. Please contact me via email if you've been having problems posting, and we can try and find a solution. Peter I can't help noticing that this happens often using OE. As well as this post of yours, I have a reply post "Subject: Bracelet inspired by a thrust bearing" by Mike in Arkansas doing the same thing - not showing the original post. Web view is fine though. Is it something in your software settings that need changing? John Peter Rowe moderator rec.crafts.jewelry |
#9
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On Sun, 17 Jul 2005 12:45:39 -0700, in ¤õ "John" wrote:
Peter I can't help noticing that this happens often using OE. As well as this post of yours, I have a reply post "Subject: Bracelet inspired by a thrust bearing" by Mike in Arkansas doing the same thing - not showing the original post. Web view is fine though. Is it something in your software settings that need changing? John John, If you can find a posting on the net, via web view (such as on Google.com's news service) that means the posting is corretly posted and has not disappeared somehow. I have, as moderator, no control over how individual ISP's news servers handle incoming posts, or even, for that matter, how they handle postings sent to the group by their subscribers. They are supposed to take those incoming posts and forward them in email to a centralized set of moderator's relay servers, who's job it is to keep track of actual moderator's email addresses, and those servers then forward the post to me. I get it in email, approve or reject it, and if approved, resend it to my own ISP's news servers. In doing this, it gets new posting headers, including a new message ID header, so it is in essence a new posting. But "reference" and "in reply to", and headers like that are retained, so the structural integrety of the post related to the group listings is maintained. That means that these posts should then correctly take their proper place in "threads", if your news reader is set up to show postings sorted that way. Posting dates in the messages are set (and must be set) to the date I resend the post to Earthlink's news servers. When earthlink gets the posts from me, they see the added "approved" header, and then propogate the postings out to the rest of usenet, and when your ISP's news server gets it, the post should then be correctly displayed. Normally this works fine, and is the way moderated groups always work.. But much depends on the way each ISP's news server is set up. Some few do not correctly handle moderated groups, either dropping posts instead of forwarding them, or not correctly displaying messages for moderated groups once they have indeed been approved. As moderator, the only thing I can do about this is to try and contact the news admin at those ISPs and call the situation to their attention. Sometimes this works, sometimes not. Subscribers to that ISP can, of course, do the same thing, and often have more clout because they are paying for service. When posts are not showing up in someones news reader, sometimes the error is in one's own news reader. OE is actually notorious for this sort of thing, since it does not always give you easy indications as to just how you've got it set up, and changing the sorting means is easy to do without meaning to, with an errant click on the header bar when reading groups. If, for example, you've got the display set to not expand threads, then the only posts you see displayed are those which begin a thread, not followups. That can be confusing if you don't realize it's doing it. And I think it's also possible, though I'm not sure, to configure OE to not show you your own sent postings, presumably on the theory that you already know what it says? Not sure about that. But check. The best way to figure out the status of a posting is to first check Google's news servers. Though somewhat slow to update (so allow enough time for me to recieve and approve a post, and for Google to then get it and post it on their servers), they do seem to have a quite robust setup, and so far, it seems to correctly handle the group's postings. So check there first. If a post is there, then it's been correctly approved and sent to the group. If it is then not in your news reader, try doing a search in the group for the message ID header, which you copied from the listing in Google (requires you to look at the full header set for the message). See if OE can then find it, and where it's hiding it from you. It may be necessary sometimes to unsubscribe from the group, clear out OE's database for the group, and resubscribe fresh, downloading all available headers for the group again. That will usually be several months worth, a long list, but you should then be able to see all posted messages that are still on the server. As to my own software settings, as you can tell from the posts headers, I use Forte Agent to moderate the group, because it functions as both email client and news client, and becuase, unlike most such programs, it gives me actual access to the headers, including the approval header (requires undocumented changes to the ..ini file, but that's easy enough to do.) Agent does seem to have some quirks. I'm never quite sure just exactly which incoming headers I should be retaining. I *think* I'm keeping all the right ones, according to other moderators I communicate with, but who knows. One odd quirk that I know originates in my software is that some incoming posts display normally when I get them, but when they make it to the group, the carriage return/line feed characters get turned into =20 sequences. It's not consistant, and no doubt has something to do with character encoding character sets between incoming and outgoing messages, but to date, i've not found an actual answer as to what I can do to change this behavior. Fortunately, it's only annoying, not fatal, to a message, and if I notice it happening, sometimes I'll take the time to manually edit out the offending extra characters when sending a message. But beyond that, as I say, the problem is likely not with my software settings, but rather somewhere else in the chain, either your ISP, your software, or one of the several servers that much correctly handle a post between you're sending it and you're seeing it again in the group listings. Hope this helps. Peter Rowe moderator rec.crafts.jewelry |
#10
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On Sun, 17 Jul 2005 19:45:44 GMT, "John" wrote:
I can't help noticing that this happens often using OE. As well as this post of yours, I have a reply post "Subject: Bracelet inspired by a thrust bearing" by Mike in Arkansas doing the same thing - not showing the original post. Web view is fine though. Is it something in your software settings that need changing? No, Mike didn't quote anything in his post. His choice. -- Marilee J. Layman |
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