Jump to content

Use Of Gemex Or Other Light Grading Systems


Chris - DC
 Share

Recommended Posts

To the jeweler’s out there, is asking for a Gemex or other comparable light performance / light grading report a reasonable request for any stone I’m considering? If I offered to pay to have the test done would that make much of a difference?

 

I’m in the market for a princess cut diamond and unfortunately have yet to find a local jeweler who I truly trust so will likely use a dealer located in another city or purchase online. To add to my dilemma I want the most brilliant and best performing princess diamond I can find in my price range and am willing to sacrifice a bit on color, clarity, and even carat size for the optimal cut and performing diamond. I realize that GIA does not grade the cut of princess diamonds (not sure if AGS does) so I am left at the mercy of every jeweler who assures me that the rock they get me will be “Ideal†cut for a princess and shine and sparkle perfectly.

 

All things considered does it make sense to ask for a Gemex or other comparable lighting report before I actually consider purchasing a stone?

 

I have a certain range of table and depth percentages I plan to stay between (looking for depth 63-72% and Table 65-74%) which I have been told increase the chances that I am receiving a well cut princess but have read the multiple posts that have explained that I can’t simply go by the numbers. But the reality is that I may have to use a jeweler located in another state and before making such a big purchase would like some other assurance that the stone will be brilliant and sparkle exceptionally well besides the jeweler’s word. No offense to any of the jewelers out there but I’m told not to simply take the word of the jeweler on color and clarity but to make sure they have a GIA or other comparable reports - so even if it’s less accurate I would like an independent report that indicates light performance. So is it realistic to ask for a Gemex or other lighting report and receive a favorable response?

 

Are there other companies besides Gemex which provide comparable light performance reports that I could ask for in lieu of a Gemex report?

 

Also, does anyone have an idea how much it would cost to get one of these reports done? I called Gemex myself and they were less than straight forward in explaining how much it would cost to have a report generated and said that my jeweler could get one done through their local branches. I may be willing to pay for the report myself for a stone that I am truly considering, so that the jeweler doesn’t bare that cost but would like to know how much they typically run.

 

I have also read the posts that explain how the diamond looks and sparkles in my own eyes is most important and no matter what any report says, I plan to return any diamond that I am not happy with once I receive it. But before I incur the expense of either traveling to look at a stone, or paying for it, shipping it back, and waiting for my refund, I would feel more comfortable with a light performance report.

 

Is this reasonable?

Link to comment
Share on other sites

Hi Chris,

If you read a lot of what's written on the internet, your approach is perfectly sound.

If you are actually looking at diamonds, not so much IMO.

Trying to buy a stone based on table and depth percentages is really not the best way to approach this situation.

AGSL does grade the cut of princess cuts- but there is controversy about what they are calling the best cuts- generally, the "Ideal" cut Princess cuts are deeper, with a smaller table and are thought to increase the fire in a stone.

But there's plenty of people who will choose a stone with a greater spread, and larger table.

it's really a matter of personal preference.

I'd suggest looking at stones in person to see which you really love before buying one.

I'd also suggest doing your homework to choose a seller, as opposed to tying to become a diamond expert overnight.

 

Personally I never use light return measuring machines as I feel they are totally irrelevant- but there are other, well respected diamond people that do use them.

Link to comment
Share on other sites

Chris;

 

Your request is entirely reasonable. You're correct in saying that there is no substitute for your eyes but what you are seeking is some corroboration. Here are the tests of light performance you should be looking at for Princess cuts:

 

1. Gemex Brilliancescope

2. Idealscope

3. ASET Scope

 

Information about the brilliancescope can be found here: www.gemex.com

 

The Idealscope is a device that is designed to measure internal light reflection. The basic principle is to surround the diamond with 2 solid colors of black and red and a white light source under the stone. Observation of the diamond through a stationary magnifying lens shows the distribution and intensity of the reflected colors.

 

Intense and uniform distribution of the internally reflected black and red colors to your eye indicates a visually "hot" stone on Brilliance, Fire and Scintillation. ImageScope performance correlates very directly with performance on the BrillianceScope.

 

A diamond is placed on a tray inside the ASET and viewed through the ASET eyepiece. When you view the diamond you see a color coded image. Colors seen are Red, Green, Blue and White and indicates the angles at which the diamond gathers and then refracts light to your eye.

 

Green = 0º (horizon) to 45º

 

Red = 45º to 75º

 

Blue = 75º to 90º

 

Black or White = indicates light leaking out of the diamond.

 

Red indicates that light is coming from angles where there is likely to be bright, direct sources of illumination in most viewing environments. This color is dominant in the ASET image of well-cut diamonds.

 

The color Blue refers to light that is normally blocked by the viewer’s head and body which usually happens when you look straight down at the diamond. An ASET image with a moderate amount of Blue indicates that the diamond has good contrast brilliance.

 

Green is produced by low-angle light, which usually is reflected from walls or other objects in the surrounding area (rather than coming from direct sources). A diamond with a high cut quality may show small amounts of this color around the bezel area of the ASET image.

 

Black or White appears in areas that do not return light under real-life viewing conditions. If a diamond is well cut, the ASET image will show only very small areas of black or white around the outer edge (and perhaps none).

 

For Fancy shape diamonds, the ASET gives you more information than the Idealscope because it takes the light return and further parses and displays it into intense light (Red) coming from the 45-75 degree viewing range and into reflected/indirect light coming from a 45 degree angle (Green).

post-5339-1236884877_thumb.jpg

post-5339-1236885089.jpg

Edited by barry
Link to comment
Share on other sites

Gemex specifically discourages using their equipment for independent evaluations of stones because their business model is to have jewelers use it as a sales tool for their own goods. They won’t even allow independent appraisers access to the machine. That makes it of not much value for what you’re trying to do although some of us can get it done through one of their dealers if you wish. If you are buying from a Gemex dealer and want to compare several stones that they have against one another, they can do it for you and if you don’t mind getting an opinion from a competitive seller about someone’s stone, some of them will agree to do it as a way of leading into a pitch for their own wares but it’s an individual decision by the dealer if they want to be doing this and it’s up to you to decide if this is worth anything. The rates are set by the retailers, not by Gemex, and they aren’t all the same so it’s not surprising that the home office people would duck this question. It keeps them out of trouble with their dealer network. Ask the jeweler who will be doing the work. They have a contact list of authorized dealers on the Gemex website.

 

Neil

Link to comment
Share on other sites

Chris;

 

Your request is entirely reasonable. You're correct in saying that there is no substitute for your eyes but what you are seeking is some corroboration. Here are the tests of light performance you should be looking at for Princess cuts:

 

1. Gemex Brilliancescope

2. Idealscope

3. ASET Scope

 

Information about the brilliancescope can be found here: www.gemex.com

 

The Idealscope is a device that is designed to measure internal light reflection. The basic principle is to surround the diamond with 2 solid colors of black and red and a white light source under the stone. Observation of the diamond through a stationary magnifying lens shows the distribution and intensity of the reflected colors.

 

Intense and uniform distribution of the internally reflected black and red colors to your eye indicates a visually "hot" stone on Brilliance, Fire and Scintillation. ImageScope performance correlates very directly with performance on the BrillianceScope.

 

A diamond is placed on a tray inside the ASET and viewed through the ASET eyepiece. When you view the diamond you see a color coded image. Colors seen are Red, Green, Blue and White and indicates the angles at which the diamond gathers and then refracts light to your eye.

 

Green = 0º (horizon) to 45º

 

Red = 45º to 75º

 

Blue = 75º to 90º

 

Black or White = indicates light leaking out of the diamond.

 

Red indicates that light is coming from angles where there is likely to be bright, direct sources of illumination in most viewing environments. This color is dominant in the ASET image of well-cut diamonds.

 

The color Blue refers to light that is normally blocked by the viewer’s head and body which usually happens when you look straight down at the diamond. An ASET image with a moderate amount of Blue indicates that the diamond has good contrast brilliance.

 

Green is produced by low-angle light, which usually is reflected from walls or other objects in the surrounding area (rather than coming from direct sources). A diamond with a high cut quality may show small amounts of this color around the bezel area of the ASET image.

 

Black or White appears in areas that do not return light under real-life viewing conditions. If a diamond is well cut, the ASET image will show only very small areas of black or white around the outer edge (and perhaps none).

 

For Fancy shape diamonds, the ASET gives you more information than the Idealscope because it takes the light return and further parses and displays it into intense light (Red) coming from the 45-75 degree viewing range and into reflected/indirect light coming from a 45 degree angle (Green).

 

Thanks Barry this is extremely helpful.

Link to comment
Share on other sites

Hi Chris,

If you read a lot of what's written on the internet, your approach is perfectly sound.

If you are actually looking at diamonds, not so much IMO.

Trying to buy a stone based on table and depth percentages is really not the best way to approach this situation.

AGSL does grade the cut of princess cuts- but there is controversy about what they are calling the best cuts- generally, the "Ideal" cut Princess cuts are deeper, with a smaller table and are thought to increase the fire in a stone.

But there's plenty of people who will choose a stone with a greater spread, and larger table.

it's really a matter of personal preference.

I'd suggest looking at stones in person to see which you really love before buying one.

I'd also suggest doing your homework to choose a seller, as opposed to tying to become a diamond expert overnight.

 

Personally I never use light return measuring machines as I feel they are totally irrelevant- but there are other, well respected diamond people that do use them.

 

Thanks -I will try to get out and check out more Princess cut diamonds although most retailers here don't carry very many.

Link to comment
Share on other sites

Gemex specifically discourages using their equipment for independent evaluations of stones because their business model is to have jewelers use it as a sales tool for their own goods. They won’t even allow independent appraisers access to the machine. That makes it of not much value for what you’re trying to do although some of us can get it done through one of their dealers if you wish. If you are buying from a Gemex dealer and want to compare several stones that they have against one another, they can do it for you and if you don’t mind getting an opinion from a competitive seller about someone’s stone, some of them will agree to do it as a way of leading into a pitch for their own wares but it’s an individual decision by the dealer if they want to be doing this and it’s up to you to decide if this is worth anything. The rates are set by the retailers, not by Gemex, and they aren’t all the same so it’s not surprising that the home office people would duck this question. It keeps them out of trouble with their dealer network. Ask the jeweler who will be doing the work. They have a contact list of authorized dealers on the Gemex website.

 

Neil

 

Thanks Neil. That would explain why the people at Gemex were reluctant to provide any price information. Do you know if there are other alternative companys that provide reports like Gemex for individual stones? Or does Gemex monolopize the market?

Link to comment
Share on other sites

Chris;

 

Here is an example of a 1.50 ct princess that exhibits excellent light performance as displayed by the Idealscope and ASET Scope. Edge to edge light performance.

 

Idealscope:

 

post-5339-1236895821_thumb.jpg

 

ASET Scope:

 

post-5339-1236895858_thumb.jpg

Edited by barry
Link to comment
Share on other sites

GCAL (www.gemfacts.com) has a ‘report’ of this sort of thing and quite a few appraisers have their own approaches to doing it but not many that offer a nationally recognized report. I use the ASET system that Barry is discussing and find it to be very helpful in comparing and describing stones.

 

http://www.americangemsociety.org/uploads/ASETTheory-709.pdf

 

Neil Beaty

GG(GIA) ICGA(AGS) NAJA

<a href='http://www.gemlab.us' target='_blank'>Professional Appraisals in Denver</a>

Link to comment
Share on other sites

Chris;

 

Just to give you an idea on how the ASET scope parses light performance, here are some more examples in the various shapes that are very popular today among consumers.

 

1.15 ct Cushion Cut

 

post-5339-1236912828_thumb.jpg

 

2.01 Asscher Cut

 

post-5339-1236912892_thumb.jpg

 

.78 Round Brilliant

 

post-5339-1236912965_thumb.jpg

 

1. Keep in mind that due to the irregular architecture of fancy shapes, light entering and exiting the diamond is significantly different from that of the round brilliant and more difficult for the cutter to harness this light and have refracted up through the top of the diamond to your eye. Hence, even in the best cut fancies you will tend to see more areas of light leakage (white) compared to rounds.

 

2. The location of the leakage (white areas) is also important. You want it to be on the periphery and not in the center of the diamond.

 

3. The 'numbers' in fancy shapes are not predictive of how the diamond will face up. Two diamonds with the same specs can look significantly different to you. Some will display a crushed ice look, others more antique and opaque. It's your personal preference.

Link to comment
Share on other sites

To the jeweler’s out there, is asking for a Gemex or other comparable light performance / light grading report a reasonable request for any stone I’m considering? If I offered to pay to have the test done would that make much of a difference?

 

I’m in the market for a princess cut diamond and unfortunately have yet to find a local jeweler who I truly trust so will likely use a dealer located in another city or purchase online. To add to my dilemma I want the most brilliant and best performing princess diamond I can find in my price range and am willing to sacrifice a bit on color, clarity, and even carat size for the optimal cut and performing diamond. I realize that GIA does not grade the cut of princess diamonds (not sure if AGS does) so I am left at the mercy of every jeweler who assures me that the rock they get me will be “Ideal†cut for a princess and shine and sparkle perfectly.

 

All things considered does it make sense to ask for a Gemex or other comparable lighting report before I actually consider purchasing a stone?

 

I have a certain range of table and depth percentages I plan to stay between (looking for depth 63-72% and Table 65-74%) which I have been told increase the chances that I am receiving a well cut princess but have read the multiple posts that have explained that I can’t simply go by the numbers. But the reality is that I may have to use a jeweler located in another state and before making such a big purchase would like some other assurance that the stone will be brilliant and sparkle exceptionally well besides the jeweler’s word. No offense to any of the jewelers out there but I’m told not to simply take the word of the jeweler on color and clarity but to make sure they have a GIA or other comparable reports - so even if it’s less accurate I would like an independent report that indicates light performance. So is it realistic to ask for a Gemex or other lighting report and receive a favorable response?

 

Are there other companies besides Gemex which provide comparable light performance reports that I could ask for in lieu of a Gemex report?

 

Also, does anyone have an idea how much it would cost to get one of these reports done? I called Gemex myself and they were less than straight forward in explaining how much it would cost to have a report generated and said that my jeweler could get one done through their local branches. I may be willing to pay for the report myself for a stone that I am truly considering, so that the jeweler doesn’t bare that cost but would like to know how much they typically run.

 

I have also read the posts that explain how the diamond looks and sparkles in my own eyes is most important and no matter what any report says, I plan to return any diamond that I am not happy with once I receive it. But before I incur the expense of either traveling to look at a stone, or paying for it, shipping it back, and waiting for my refund, I would feel more comfortable with a light performance report.

 

Is this reasonable?

 

 

It is a reasonable request, however most jewelers don't have the capability of having the equipment to do the tests. It is quite expensive. We've had the brilliancescope for over 9 years now, we were the first bricks and clicks to get it. It has really helped us to buy better looking diamonds over the years as well. Also have had the Isee2 probably for over 6 years now. They are kind of similar except the Isee2 takes the symmetry into the equation as well as the light performance.

Let me know if we can be of any help to you to find your dream stone.

Edited by jan
Link to comment
Share on other sites

Gemex specifically discourages using their equipment for independent evaluations of stones because their business model is to have jewelers use it as a sales tool for their own goods. They won’t even allow independent appraisers access to the machine. That makes it of not much value for what you’re trying to do although some of us can get it done through one of their dealers if you wish. If you are buying from a Gemex dealer and want to compare several stones that they have against one another, they can do it for you and if you don’t mind getting an opinion from a competitive seller about someone’s stone, some of them will agree to do it as a way of leading into a pitch for their own wares but it’s an individual decision by the dealer if they want to be doing this and it’s up to you to decide if this is worth anything. The rates are set by the retailers, not by Gemex, and they aren’t all the same so it’s not surprising that the home office people would duck this question. It keeps them out of trouble with their dealer network. Ask the jeweler who will be doing the work. They have a contact list of authorized dealers on the Gemex website.

 

Neil

 

There was an appraiser that had it at one time. It's a little more than a sales tool. It can kill a sale just as much as make one.

Link to comment
Share on other sites

Here is a comparison we had just the other day between two princess cuts. One is a stone we had in stock and the other was purchased by someone from bluenile that brought it in.

 

You may be able to see the difference in the photos I took, it is more obvious when you see them in person. The one from BN on the right has less brilliance in the center to my eye.

 

Testing them out on the isee2 unit it picked up the same thing with the BN stone scoring a low of 2.

 

 

post-114043-1236960807_thumb.jpg

 

post-114043-1236960832_thumb.jpg

 

post-114043-1236960848_thumb.jpg

Link to comment
Share on other sites

The microscope is a sales tool too. So is the Sarin machine, diamond scale, loupe, tweezers, gemex, Isee2, color comparison stones, GIA reports, AGS reports etc. All these I`ve used in a sales presentation. I didn`t know it was against the law to sell diamonds. :rolleyes:

Link to comment
Share on other sites

Hi David;

 

I respect your position regarding these various tools to measure light performance and of course they are not a substitute for actually seeing the diamond.

 

However, for those consumers shopping on-line it does provide valuable and useful information especially when the Vendor in addition also has the diamond in-house so that addional questions canbe answered accurately.

Link to comment
Share on other sites

There's nothing wrong with sales tools. The difference with the Gemex and Isee2 folks is that they deliberately limit it's use for anything else, like for example the request being made in this thread. A microscope manufacturer, Sarin, the makers of Idealscopes and ASET's, even GIA will sell tools to whoever wishes to pay their price and encourage their use.

 

 

The fact that one appraiser once had one for a while a few years ago hardly changes this.

 

 

Neil

Link to comment
Share on other sites

I agree guys- just talking to someone about a diamond is a "sales tool".

There's noting inherently wrong with a sales tool- but how it's used is the issue. Brad himself mentions how it's possible to see the difference in person.

Is everyone going to choose Brad's diamond, or the BN stone? I don't believe this is a 100-0 situation.

If we can prove that Brad's diamond is more brilliant based on ISEE2 or Gemex or IS, does that mean it's better?

What if someone still likes the look of the other better? Are they "wrong"?

My personal opinion s that many of these tools eliminate some amazing diamonds and are no substitute for actually looking at the diamond. I also feel that the use of these tools is so heavily promoted by some sellers ( present company excluded) so as to make them less than helpful.

I get Barry's point- and appreciate the opportunity to discuss both sides of this very interesting story.

Link to comment
Share on other sites

David;

 

I believe we are actually in agreement on this issue.

 

There is no substitute for actually seeing the diamond.

 

Indeed, a consumer may prefer a diamond with the "numbers" not being as 'good' as the comparison diamond e.g.; a round diamond that has been given a Very Good Cut Grade compared to an EX Cut grade. We have seen this many times in our Showroom. In real life actuality, the difference between a VG cut grade to an EX Cut Grade is microscopic and totally invisible to the eye.

 

As far as Fancies are concerned, this is even more true as a combination of "numbers" that fall outside of dogma or charts/tables may indeed face up better than a diamond that has been defined as "Signature" or "Ideal".

 

Where these tools do serve as a valuable resource is for the Internet shopper, for it allows him/her to 'see' the diamond with some indication of its face up light performance. Photo's are also important. A very critical add-on is for the selling Vendor to physically have the diamond in front of him so that he can check for red flags that will not be apparent just for the lab grading report. Indeed we have a current running thread on this Forum where the OP purchased a SI-2 clarity diamond from a drop-shipper who never examined the diamond and just accepted the word of the Manufacturer. Upon receipt of the diamond, the OP reported that she clearly saw a black carbon under the table and returned the stone.

Edited by barry
Link to comment
Share on other sites

Not only do we agree Barry- but if I had to name a seller that really does balance the use of these selling aids with more practical methods, it would be you.

 

The lady who got the non eye clean SI2 would not have been helped as much by IS, ASET or GEMEX as she would have been by good digital photos.

I am amazed at how many people are willing to buy such stones sight unseen.

Link to comment
Share on other sites

Not only do we agree Barry- but if I had to name a seller that really does balance the use of these selling aids with more practical methods, it would be you.

 

The lady who got the non eye clean SI2 would not have been helped as much by IS, ASET or GEMEX as she would have been by good digital photos.

I am amazed at how many people are willing to buy such stones sight unseen.

 

 

Good point.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
  • Create New...