What''s the best lighting in which to judge the color of a diamond

[Rockdiamond]

HI everyone!

Looking at how gem labs, and gemologists grade the color of diamonds, it''s different than the way many traders or dealers do so.

IN the case of gem labs, or the better gemologists, a light box is used to ensure consistency. At GIA and other labs, the room is generally blocked from outside light( sunlight).

In contrast to this, the "traditional" method would use fluorescent lights situated in a space with a lot of natural daylight- the preferred light is diffused sunlight from a north facing window.
This was how it was done at Harry Winston when I was trained.
In contrast to grading rooms at GIA, the trading areas in the various "Diamond Clubs" generally have large windows, with a lot of natural light. A lot of dealers still use natural light to help decide.


My feeling is that natural lighting is essential in deciding whether or not to purchase a diamond- I would include consumers in this.
I don''t suggest having direct sunlight be the only place you look- but natural sunlight should be one of the environments used.

My reasoning; In the need to make things consistent, I feel that we loose some of what we need to make judgements.
Unless one lives in a box, a large percentage of diamond or jewelry viewing will be done in the presence of natural lighting. Therefore, how it looks in natural lighting is very important.

Which works better for you?

 

[Todd Gray]

We may not "live in a box" but "grading in a box" and "in the dark" provides a consistent environment for diamond grading which can be duplicated regardless of time zone, location on the planet, cloud cover, etc. which is why we "grade in the box" and "evaluate" under a variety of lighting conditions... Heck, a slight variation in the tone of a white wall or the temperature of lighting in a room could affect a diamond by several color grades - why wouldn''t a diamond professional grade in a consistent environment David?

If you want a D to be a D in NYC / Antwerp / Tel Aviv / Bangkok / etc. you "grade in a box" but I guess if you don''t mind a "my best guess" based on the output of the weather monkeys at the moment, you grade in an open room.

BTW: "weather monkeys" comes from my belief that the weather report is predicted by a bunch of monkeys sitting around in a room, armed with a handful of darts aimed at a dart board used to "predict the weather"

 

[Rockdiamond]

Great point Todd. Thanks for adding your valuable point of view.

I agree that for the strict purpose of grading, consistency is key.

However, "Grading" and "Evaluating" have different goals IMO. Especially if a purchase is contingent on evaluating.

After all, some D''s are a lot nicer than others.

Would this mean you suggest shoppers use artificial lighting?

 

[Rockdiamond]

One other thing that relates to this,touched upon by Todd.
If one does their buying overseas, many diamonds still look different when you get them back to home- even if you brought your own equipemnt and lighting.
I've spoken with many dealers that purchase overseas who have also felt this way.
Maybe it's the water

 

[Todd Gray]

Date: 9/16/2009 5:57:09 PM
Author: Rockdiamond
One other thing that relates to this,touched upon by Todd.

If one does their buying overseas, many diamonds still look different when you get them back to home- even if you brought your own equipemnt and lighting.

I''ve spoken with many dealers that purchase overseas who have also felt this way.

Maybe it''s the water

Which is why I love having parcels shipped in so that I can evaluate them in my own environment with my own equipment! There is a traditional B&M up the street from me who advertises that he goes to Antwerp to buy diamonds (twice per year) on behalf of his clients (as a pre-paid, pre-order only) as part of a jewelers group... The advertising executive for the local radio station literally blew coke out his nose when I said I wanted to run an ad campaign along the lines of "Why would you want to pay for your jewelers vacation to Antwerp? As a Direct Diamond Importer, we have parcels of diamonds being flown in from Antwerp at least twice per week! Why don''t we fly to Antwerp? Well, first of all, we don''t see the need for the added expense; and secondly we like to grade the diamonds in a reliable grading environment using OUR lab equipment - not the cutters!"

Sadly, the radio guy didn''t want to play

 

[Rockdiamond]

I could not agree more Todd!
I love the fact there are a lot of very large cutters in New York, making overseas buying less important.
I think your ad would have been perfect!

(PS- maybe if the guy wasn''t doing Coke he''d have been more open minded

)

 

[Diamondbug]

I have nothing to add since I know zilch but I wanted to say I enjoy your bantering and your post is always interesting and informative. You post questions that never cross my mind. I know they grade next to a master set but to have to worry about wall paint and lighting too? Makes sense now that you brought it up... but who knew.... Thank goodness for people like you guys, makes for an educated buyer. THANK YOU!

 

[denverappraiser]

It’s perhaps unfortunate but most people, at least in America, DO live in boxes. We go from our homes to our cars to our offices to to stores and restaurants and back again. All of these places are lit by artificial light either fluorescent, incandescent or led. Even the natural light we encounter is almost always filtered through glass of unknown optical properties or through clouds, smog, shade or a combination of all of these things. Direct sunlight has become a rarity for nearly everybody, not just the people who live in Seattle. By all means it’s good to evaluate stones in as many lighting environments as possible, including direct sunlight but for nearly everyone this is distinctly a fringe environment.


Thank you for pointing out that grading diamonds is different from evaluation. The folks at Harry Winston and GIA are grading stones upside down against comparison masters to pick which one has the most color saturation. This is a decidedly different task from what consumers are looking for. They’re inspecting the stone face up for some personal sense of what is most beautiful. Unfortunately, our eyes respond to bright lights in some funny ways and a well cut diamond viewed face up in direct sunlight can be a VERY bright light. For purposes of evaluating color this is a terrible environment.

I would also like to reiterate a point made by both you and Todd. For grading purposes, repeatability and consistency is the key. Todd’s preference to grade using his own lights is not a disparagement of the lighting used by the folks in Belgium or a statement that his lights are ‘better’. The folks in Antwerp would surely say the same and prefer to use the lighting they are familiar with and eschew grading in his lab. They can both be right. I don’t know if it’s the best for evaluating color but the Colorado sunshine is great for using those super-ideal cut diamonds that y’all like to sell to interfere with passing air traffic on the way to LA.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

 

[Rockdiamond]

HI Diamondbug!
You are so very welcome- and I think you DO have something to add to the conversation!

Hi Neil!
You grouped the folks at Harry Winston together with GIA.
In fact, the graders at Winston would be more interested in evaluation, as opposed to strict grading. I believe that is what a consumer should also be doing.

My experience regarding natural light is different than yours.
I find that much of my days are spent in places with a lot of natural sunlight.

You have mentioned that glass filters out a lot of the UV rays- but again, my experience is different.
When I look at fluorescent diamonds in sunlight coming through our windows, the UV content of the sunlight is instantly noticeable.
In fact, if I held a diamond in direct sunlight, while holding a UV spotlight directly on the diamond, the sun would have a far greater effect- even coming through glass.

I think this also goes to the differences between grading, and evaluating.
In most cases, it would seem that an appraiser would be called upon to do both- but maybe placing a higher priority on the former.
A trader had better do both. Or they won''t be a very successful trader!

 

[Rockdiamond]

BTW- thank you for participating Neil- I value your viewpoint a lot.
I believe there is a difference in the way a diamond is looked at by a gemologist, versus a trader -consumers are traders as well. The trader needs to "judge" a diamond, to see if it's worthy of purchase.
I'm sure you're called upon to do that all the time- with good cause- I'd trust you to pick out a diamond for me anytime!
But if your task is to grade, it would need to be different than judging.
GIA never judges a diamond. Grading must be done impartially.
An ugly as sin stone can be a D/Internally Flawless.
GIA will never recommend a diamond, nor dissuade someone, other than issuing a grade, and grading report.


Back to the color, and how it's looked at.
If your job was to match diamonds for earrings, wouldn't it make the most sense to do it face up?
in some senses, that's a "practical" method to grade the color.
I would always suggest consumers judge the color face up as well.