Gemstone and mineral photography and it's lighting

[Barrett]

I got bored about a month ago and decided to write up this little tid-bit. I figured I would cover as best I could the other half of photography: Lighting. The only reason photography and shooting gems and minerals is possible is light.
In my opinion 30% of taking a good photo is all camera and the other 70% is lighting. Lighting is very very important if it's 70% of taking a good picture. Lets start off with light itself. Light is brightness that comes from an object such as the sun, a fire, a flashlight, or a lamp. All light comes from atoms. Atoms that produce light have either gained energy by absorbing light from another source or by being struck by other particles. It is this 'extra energy' that causes an atom to give off light. The light being emitted is carrying off the extra energy.

Now when discussion light and color we must explore waves as well. Waves have high and low points, and the distance between one of those highs and lows and the next is called a wavelength. Just how long that wave is will determine the amount of energy that it has. For example, a long wave has a low amount of energy or low frequency, and a short wave has a high amount of energy or high frequency. What we see in a rainbow, then, are the wavelengths of the visible colors. You see, our sun emits its radiation in this visible range, which our eyes interpret as the colors of the rainbow. These colors are identified as the visible spectrum. Thery are red, orange, yellow, green, blue, indigo, and violet.
Light travels in the form of a wave. It is basically photons (pieces of energy or particles), and mostly moves as waves. White light, or the light from the sun or lamps, is made of colors, and colors are different types of light recognized by their own wavelengths. The color of anything depends on the type of light sent to our eyes; light is necessary if we are to have any perception of color at all. An object is "colored" because of the light it reflects—all other colors are absorbed into that specific object. So then, an Sweet Home Rhodochrosite appears red because it reflects red light. Let me also add before I move on, that three things can happen to light. It can be reflected, absorbed, or transmitted. I will get to that later if I remember(note to self remember ;D)

Now to lighting and photography now that we have an understanding of what light is. When it comes to lighting they make a big difference it what you preceive or the camera preceives. That is due to kelvin temperature. Kelvin temperature, also called color temperature, is very very important when shooting gemstones and minerals. Here is the definition from wikipedia
"Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, and other fields. The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of comparable hue to that of the light source. Color temperature is conventionally stated in the unit of absolute temperature, the kelvin, having the unit symbol K."

Color temperatures over 5,000K are called cool colors (blueish white), while lower color temperatures (2,700–3,000 K) are called warm colors (yellowish white through red).

This is were having the proper lighting comes into play. The white balance on your camera should actually be called the "color correction". It helps to change the color temperature in whatever light you might be using. It's not as good as actually using proper lights but it's a simple and easy way to make those small adjustments to help show what you are seeing in real life.
Here is a color temperature chart to show what some common temperatures are.


Here is another one which will also give you an idea of what color temperature is.


So what does this all mean? If you notice it has a color which corresponds with a temperature which corresponds with a type of light/lighting. This plays a big role in shooting gemstones and minerals. It determines what light you use and what background you use. It also correlates with what color gemstones and mineral and what color background you are using.

The reason you see many photos on white or gray background is it gives purity of hue(color) to whatever gem or mineral you are shooting and white is generally good for high-contrast or high key shooting If you choose to use a background with color the accepted idea is to use complementing colors which are opposite the color wheel from the color of the object you are shooting. The only problem with using a colored background is it affects the sensors on your digital cameras. So if you are shooting a red beryl crystal on a green or blue background, even though the camera sensor is directed onto the red of the red beryl crystal light bouncing off the green or blue background is coming into your camera sensor and messing up what the camera see as the red in the red beryl crystal. This may not sound like that big a deal as the slight color variation is not huge but when dealing with gemstones even the smallest color change can be the difference between a good colored stone or an okay stone or $10 and $10,000 when showing or trying to sell a stone. If you notice on many of Jeff Scovill and Joe Budds photos they will superimpose whatever gem or minerals they took a photo of onto a colored background rather than actually shooting the photograph on a colored background The preferred background color for purtiy of color is white or gray.


Here is an example of what a colored background can do to a stone. You can adjust the white balance but it will either take away from the stone/specimen color or the background color. You can't have it both ways. The sensor is picking up the stone(pakistan moonstone) color but the light reflecting off the blue background in skewering what the sensor sees. Some sensors also take the pixels next to other pixels and use algorithims to determine what color the sensor is seeing but that is a discussion for a whole different time and place.

 

[Barrett]

True color of stone


Now to lights.
There are 3 main types of lights which we all know and use. Sunlight, fluorescent, and incadescent. There are many what I call minor type lights including tungsten, halogen, high pressure sodium, metal halide, mercury vapor, xenon, LED, etc. but we will just stick primarily to the main 3. Standard fluroescent lights typically have a bluer component to them and incadescents more of a yellow component and sunlight at noon in summer having a perfect blending of all colors(white light). Sunlight at different latitudes, at different times of day, and how clear the sky is depends on which direction the color in sunlight leans towards. Shade from a partly cloudy sky will leanb more towards blue and early morning or evening sunlight will lean more towards yellow and red.


What does all of this mean to us? It means when we shoot minerals or gemstones of a certian color we want to use the proper light to help show an accurate picture and/or add some vibrance to the gem or mineral. I will disregard sunlight since it can be finicky and not listen to our pleas and moans also it can be damn cold outside which neagtes my lazy butt from shooting anything out doors. If you are shooting a tanzanite crystal what type of lighting would you want to use? You would want one that leans more towards the blue end of the spectrum. That would be a fluorescent light(partly cloudy day). Not all fluorescents lean towards the blue end of the spectrum. Schools and hospitals are closer to 5500K above and below, most retail stones 4100K, and offices anywhere from 3500K to 6500K. If we were shooting a heliodore what type of lighting would we want to use? Incadescent? Nope. The reason being..if your perfect light is sunlight at noon on a summer day which equals 5500K(kelvin) then incadescent is way to far below on the color temperature chart from the "perfect" light at 5500K. Incadescent being on average 2600K-2800K. That is 2700K-2500K below what the "perfect light is. The fluorescent light, which we used for the tanzanite crystal, averages 6500K(also called daylight bulbs). Thats only 1000K difference from the "perfect" light(sunlight). This is the reason why you never use incadescent light to shoot gems or minerals, which most of you already know. What would I want to use to shoot my helidore crystal then? I would prefer someting close to perfect but maybe with a little yellow added in naturally. That means anything below 5500K starts to add some yellow and red to my specimen. The more I go down in Kelvin(color temperature) the more reds and yellows I add. You don't want to go so far as to skewer the accurate color of the specimen you are shooting but you want to add a little more color to it. Now you might say "This will not give an accurate color to the person looking at the photo"! It all depends on how it's viewed in real life. If I take the photo under fluorescent light then take the gemstone to John Doe's house and he looks at it under the lamp in the family room it will be a different color than the one in the photo. If I take a picture of a gemstone under sunlight then bring it to an office, school, or Wal-mart it will look different under the fluorescent lights they have than it did in the picture. Here is a picture showing a 3500K fluorescent(left) and a 6500K fluorescent(right). You can see the huge difference between the two and you can understand how each one will affect the color of the gemstone or mineral you are shooting.


My blue, purple, and green specimens and gemstones I like to use my Ott 6500K fluorescent lamps. When I shoot yellow, red, or orange specimens I like to use my Solux 4700K bulb. The Solux light is a halogen(3000K) but it has a special filiment and reflector which brings it to the 4700K mark. Solux light are the creme de la' creme of lighting. They are the same lights you see in highend dealers booth in Tuscon and at most gem shows and at the Smithsonian . Here is the snippet from Solux:

"The SoLux daylight lamp is universally recognized as the ultimate in D50 daylight simulation. Independent studies have concluded no other man made light source comes close (see volume 3, March 1999, Journal of Prepress & Printing Technology, Quantifying illuminant Metamerism of D50 simulators). Recommended and specified by art museums, galleries, world renowned photographers, Fortune 500 companies like Dupont and BASF."

I have 2 Ott light for taking photos and 1 solux lamp,some tungsten bulbs, different halogens, photo bulbs, and a little of everything in between. My basic setup I use my 2 Ott lights and my solux. All others I only pull out for specific reasons or specific gems and minerals. This shows my basic setup of lights and pods.


When it comes to light tents I have 4 of them, well actually 3 and a half. Two of them are real light tents I bought and one I made and the 1/2 one I made and use for taking photos of only gemstones. I find light tents useless and not worth a darn. I used them a few times and realized they really added nothing. I also know of no dealers or gem sellers that use them. Most will have at least one but they don't use them. A waste of money in my book. The only way to properly shoot gemstones is to use a light tent but it is not your standard light tent like we all think about. Hopefully I will get to that at a later time.

Here are some examples of different lighting and stones but first let me talk about color shift real quick.
Most of you have heard of color change or color shift gemstones. You see them being sold all over the place. Color change gemstones are just that...color changers. They change color or flip across the color wheel. If a color change moves from lets say Red to the next color on the wheel (orange) then this is called a Color Shift. If the color moves from Red to Green, which is on the other side of the wheel, then this is called Color Change. All gemstones and minerals color shift to some degree. Some do shift more promounced than others but all do to some degree anyways.

Okay first...this tanzanite crystal. Same axis... same crystal....different lighting.

Fluorescent(6500K)

 

[Barrett]

Incadescent


You can see the huge change in color just from using the different type of lighting.

Here is a paraiba crystal.
Note the rich vibrant blue under 6500K fluorescent


Now I use the 4700K bulb. Much less blue..not to bad but nothing like the 6500K bulb


Now for incadescent(75watt 2700K). Horrible. Almost no good blue showing.

 

[Barrett]

Here is another example of a blue and purple bi-color cuprian crystal
2700K


4700K


6500K


I used blue specimens to show the huge difference. This is because blue is a primary color. Now lets look at green, which is mixture of yellow and blue. Since green is not a primary it's color shift in different types of lighting is less pronounced. Take this peridot for instance
Incadescent 2700k

 

[Barrett]

4700K


fluorescent 6500K


Not much of a difference between the three especially the 2700 and the 4700. The 6500K to me looks a little better since it helps take more of the yellow out and adds blue which makes for a richer green. The 2700 and 4700 and adding some yellow to the stone and since green is made of yellow and blue it's now trending more towards the yellow side which is an undesirable trait when looking for purity of color and in the case of peridot that would be green.

Lets now look at a stone which is in the red/orange/yellow side of the color spectrum. This pre-formed spessartine garnet is orange as well all know. Lets look at it under fluorescent light first(6500K)


Notice how brown it looks. That is because when you add blue(fluorescent 6500K) to red/yellow(orange) you will get brown. That is why the stone appears brown in the photo.

Now lets see it with more of a yellow added by using the 4700K and the 2700K incadescent.
4700K

 

[Barrett]

2700K


Note how much better an orange it has. The 4700K adds some yellow but the2700K adds a lot of yellow and it even adds orange since orange starts around 2800K on the temperature chart. The incadescent picture has the littlest amount of brown since incadescent has less blue in it's lights wavelength.

I have many more examples of pictures in my recycle bin on the computer from when I used to sell. When I would sell sphene, rubellite, almandine and namanga garnets, spessartine, and my yellow tourmalines from kenya, etc. I would use my Solux 4700K to take photos with but when I sold my blue and green tourmalines, tanzanites, hauyne, paraiba, etc. I would use my two Ott lights.

I didn't get a chance to add anything about setup or light positioning and a few other things. Michael E., Gene, Jamey, TL, LD, Freke, or anyone else feel free to add any corrections or more info as seen fit.

 

[colorluvr]

The only way to properly shoot gemstones is to use a light tent but it is not your standard light tent like we all think about. Hopefully I will get to that at a later time.

Impatiently waiting for "later time"..

 

[LD]

Amguy - thank you for the photos showing how each gemstone looks in different lighting conditions. Fascinating stuff. I guess you know what I'm going to ask now? Which one replicates what you see IRL please?

 

[mrswahs]

Now, under those different lighting conditions, if you were to use a custom white balance, shouldn't they all look the same?

 

[Michael_E]

Now, under those different lighting conditions, if you were to use a custom white balance, shouldn't they all look the same?

The white balance just balances the color of a white card under the lighting conditions present. Gemstones are not white, so the white balance doesn't affect them much. Gems are a filter which absorbs some colors and lets other colors through. If a gem passes red and blue light the color you see depends on the amount of each color in the light entering the gem. If that gem is in a high color temperature environment it will look more blue, since there's more blue entering it. In an environment with more red light, like sunlight or incandescent , the stone will look more reddish. Amethyst shows this very clearly even though it is not considered a color change or color shift stone. It's as much about the light entering the stone as the properties of the stone itself. You camera sees colors differently than you do and in many cases the only way to get an accurate color of a gem in a digital photograph is to change it with photo-manipulation software, (Photoshop, Corel, etc).

 

[T L]

Now, under those different lighting conditions, if you were to use a custom white balance, shouldn't they all look the same?

The white balance just balances the color of a white card under the lighting conditions present. Gemstones are not white, so the white balance doesn't affect them much.

I actually disagree with this. I have noticed that if my white balance isn't just right, my gem colors alter dramatically. I know my white balance is correct when my fingers do not look corpse colored in the shot. I often take photos of my rings while I'm wearing them. There's a reason for that. I always adjust the white balance to ensure that my skin looks normal color. That's my little trick to ensure some accuracy of the color in my shot. I do not manipulate the photo after that except in Paintbrush, where I just crop.

BTW, thanks to Amguy for the informative new thread.

Amguy,
I have a stone that has no discernable color shift, no matter the lighting. I will post pics later tonight. It's the oddest thing. All my gems change a little bit to a great extent (color shifters), but this particular one does not. I don't get it. It's a pink tourmaline. Very bizarre.

 

[T L]

This is the strangest gem. I've had it for over a year now and recently set it in an old reused LOGR legacy. I would set it in something nicer, but I suspect it's irradiated. It's a Nigerian pink tourmaline and it has some needle inclusions. It does not shift color, no matter the light source. I suspect it's irradiated because I heard that irradiated tourmaline (blue or pink) does not shift. Here are photos taken in incandescent, fluorescent and sunlight on an overcast day. If it looks slightly different in each photo, trust me, the color nuances aren't there IRL. It has beautiful color to me, but I've never seen a stone hold it's color like this!

 

[T L]

Super up close shot of inclusions

 

[Barrett]

WOW..there is pretty much no difference between the fluor. and the incad. That is very strange. I was trying to think..since pink is a tint of red you would think that the red in a lower K bulb would bring out more red in the stone. Like we have all said before in the past...all gems color shift to some degree. Of course, some do so more than others but it seems as if yours doesn't at all


Hey LD, I like to use my 6500K bulbs the most. Sometimes I get a little funky and add some of my 4700K light to a stone while using my 6500K. I would like to think it balances out close to 5500 but that maybe wishful thinking. Lets see 6500K is 1000K away from the perfect light, which is 5500K, and 4700K is 800K away from 5500K so thats 200K away from the perfect 5500K. I like to think that but not sure if thats true IRL...LOL. I learned from many of you on pricescope as to why it's so important to ask for pictures in different lighting when buying a stone. School, the office or work, Wal-Mart, and hospitals all have fluorescents but most homes have incadescents. It's good to know how it will look at home or out and about shopping or at work

 

[Barrett]

OHHH...I just love that camera. You did good before(old camera) with showing color but this new one shows the color and it's in focus which your other camera had trouble with. Isn't it so fun taking new photos of your gems and playing around with your new toy

 

[Arkteia]

I bought the solux bulbs and stand but part of the order has been backordered so I can not use it yet. In the meantime...
Many people have mentioned "diffused" light and "milk bottle trick". I am just trying to understand... You have to cut out the bottom of the milkbottle to manipulate the stone inside it, right? And cut out an opening for the camera in the side? Or do you do it some different way. Sorry for naive question, but several people here have mentioned it as a "cheap way to diffuse light", so I assume it is well-known...

 

[kenny]

In your pics the background's color varies.
The same background should be the same color in all pics, regardless of what light source was used.
When it is not, it is a warning sign of operator error.

If you manually white-balance the camera for every light source before taking every pic [the old-fashioned time-consuming way - by pointing the camera at a white or gray card and pressing the white-balance NOW button or whatever your camera calls it, instead of depending on the camera's "automatic" white balance] wouldn't the exact same background be the exact same color in every pic?

If it is not the same the exact same color, there is a white balance issue.
Don't even bother looking at the gem until you get this mistake corrected.

Think about it.
How can you expect a camera looking at a red gem on a red background under a reddish tungsten light to know what the heck to use as a reference for white balance?

Another example of the false-promise of technology turning our brains off.

 

[Barrett]

Hey Cras, how are you? Hope all is well!!
What Kelvin bulbs did you get? Solux are what you see at all the gem and mineral shows. Most big dealers have solux bulbs which is where found out about them. I got the 4700 but I want the 5000K. Make sure and get you some fluorescent bulbs to take photos of your bluer stones under. You can get Ott lights at Jo Ann's fabric store. I got mine after cutter Roger Dery recommended them.

From the Solux website
"What is SoLux?
SoLux is a patented light source that provides an unparalleled replication of natural daylight. Use of SoLux in many of the world's top museums including the Musee d'Orsay, Van Gogh, and Guggenheim Museum is testament to its unmatched color quality. SoLux also has eight times the life and twice the efficiency of standard incandescent sources, does not contain the mercury found in fluorescent lights sources, and is a fraction of the cost of LED sources. SoLux is now available in line voltage PAR format. To purchase SoLux click on the Products tab above.

SoLux is a patented light source that provides an unparalleled replication of the daylight spectrum. SoLux has been tested, approved, and recommended by the worlds most exacting color experts in various disciplines ranging from museum lighting, light therapy, photography, digital color proofing, automotive paint finishing, and machine vision. SoLux is currently available as a 50 watt and 35 watt, 12 volt lamp in a standard MR-16 format. The base for MR-16 light sources consist of two pins that plug into a female socket. SoLux emits daylight at correlated color temperatures of 3500K(± 200K), 4100K(± 200K), and 4700K (± 200K). The 3500K, 4100K,and 4700K SoLux bulbs have a lifetime of 4000 hours, unsurpassed color rendering indices, and ultra-low ultraviolet and infrared radiation. They are available in two wattages, 35 and 50 watts, and four beamspreads 10°, 17°, 24°, & 36°. SoLux also comes in a color temperature of 5000K(D50) (± 200K). The 5000K is available in 35Watts and 36 degrees. Click here if you would like definitions of terms used above.

An Independent evaluation of SoLux has recently been published. The results showed SoLux produced a daylight spectrum far superior to any competing daylight source. Below are graphs summarizing the findings. The black line is D50 and the green line closely following it is SoLux. The CRI values average 98.3. For a copy of the report go to BabelColor

another page--3. Jewelry Stores - Thousands of jewelry stores around the world already are taking advantage of the superior presentation provided by SoLux to best highlight their fine diamonds, gem stones, and precious metals. 3500K is the most common choice of jewelers for gold and the entire store, however, some jewelers prefer 4700K for their diamonds and 4100K for their gemstones. We recommend choosing one color temperature unless separate viewing rooms are available

 

[Barrett]

how it works

 

[Barrett]

Here is from John Betts fine minerals page. He is one of the highest end mineral dealers in the entire world

Lighting
Probably as important as camera selection is lighting. Digital cameras have built in white balance to compensate for the color temperature of the light source. It is relatively easy to compensate the color for a specimen illuminated under incandescent light, something not easily accomplished with conventional photography. However it is important to use a full spectrum light source. For example, a 60 watt incandescent bulb has very little blue/purple in the spectrum of the light it outputs. A mineral specimen with dark blue (i.e. azurite) on a black matrix illuminated under incandescent light will render both colors as black. No amount of photo manipulation on the computer will ever differentiate the two colors. By using a full spectrum light source that problem can be minimized.

Also the light sources should be small, adjustable/moveable lights that produce a broad illumination without strong hot spots, either by use of frosted bulbs or additional diffuser. This is required to control the reflections off individual crystal surfaces, without harsh hot spots - very important in mineral photography.

The one light source that meets all of these needs is the new SoLux halogen bulbs. This is a new technology lamp based on MR-16, 50 watt halogen bulbs, but with proprietary technology to produce a full spectrum light output. SoLux has been so successful, they have been adopted by several museums as the standard light source for their paintings and exhibits. SoLux bulbs are available in several different color temperatures. The Solux bulb best for photography is the 4700° version which is the equivalent to daylight at 10:00 A.M. and very close to 5000° Noon daylight. (35-mm photographers can use an 80D filter to convert SoLux illumination to conventional daylight film.) For digital photography, Solux bulbs are perfect, yielding accurate rendition of difficult to photograph minerals like dioptase and azurite. They are 12 volt bulbs and fit in any light fixture that can accept an MR-16. Solux also manufacturers a task light to hold Solux bulbs with highly adjustable swivel arm that works well in photography, display or even illuminating specimens under a microscope. I use the widest angle bulb (flood) which has a spread over 30 degrees. But any of the Solux bulbs will work

 

[T L]

In your pics the background's color varies.
The same background should be the same color in all pics, regardless of what light source was used.
When it is not, it is a warning sign of operator error.

If you manually white-balance the camera for every light source before taking every pic [the old-fashioned time-consuming way - by pointing the camera at a white or gray card and pressing the white-balance NOW button or whatever your camera calls it, instead of depending on the camera's "automatic" white balance] wouldn't the exact same background be the exact same color in every pic?

If it is not the same the exact same color, there is a white balance issue.
Don't even bother looking at the gem until you get this mistake corrected.

Think about it.
How can you expect a camera looking at a red gem on a red background under a reddish tungsten light to know what the heck to use as a reference for white balance?

Another example of the false-promise of technology turning our brains off.

Kenny,
I will admit, I have problems with white balance in dim artificial lighting (my home and office). In my camera, you can do auto white balance, which just gets totally messed up for me in dim artificial light, or choose one of the settings for incandescent or fluorescent lighting, which seems to work better for me in dim artificial lighting. I don't like taking photos in artificial light because they're never as accurate, but please trust me that this stone shows no color shift to my eye. It's actually a bit disconcerting as I feel it might be irradiated because of this. Please remember, I have a cheapie point and shoot, and you can only do so much with white balance, but I will say the auto white balance works much much better in natural or bright light. Maybe I just need more lighting, but I don't know where to get it unless I go shopping at the grocery store!! LOL!

 

[Barrett]

Here is from Richard Wise blog

Lighting and Grading Gemstones Part II

LIGHT UP YOUR LIFE



by Richard W. Wise, G.G.
© 2006



What is the best lighting environment to view gemstones? In part I of this post I discussed the various lighting options and the pros and cons of each. In part II I will write about the lighting some of the world’s foremost gem experts and connoisseurs choose to both view and evaluate gemstones.

Among the experts opinions differ somewhat as to which “daylight” Kelvin temperature is best but each accepts daylight as the standard. Stephen Hofer one of the world’s most respected authorities on colored diamonds, maintains that 5500K works best for colored stones and 6500K is best for diamonds both white and colored. In his lab, which is dedicated to the evaluation of fancy color diamonds, all grading work is done under 6500 Kelvin fluorescents. C. R. Beesley, President of American Gem Labs in New York, prefers Vitalite a bulb manufactured by The Duro-Test Corporation with a Kelvin rating of 5500. "Most people don't do their homework", says Beesley, "comparing color temperature isn't enough..." Beesley tested more than twenty different light sources in the process of developing his Colorscan colored stone grading system to gauge their actual effect on gemstones.

In 1994 GIA completely revamped its color grading system for colored diamonds, shifting from Veralux, a so-called low UV lamp rated at 6200K, (see Secrets Of The Gem Trade, p.60, fn) which remains its standard for grading colorless diamonds to a 6500K average daylight fluorescent bulb for grading colored diamonds. The lamp is manufactured by Kollmorgen Corporation. GIA also uses a 6500K for general research purposes. The Institutes use of light of this Kelvin temperature is in no way an endorsement of the use of this type of lighting by jewelers. According to James Shigley, GIA's Director of Research, 6500 was chosen because it is a recognized standard used by color scientists. Little or no thought was given to enhancing the beauty of gemstones.

Incandescent and quartz halogen lamps can be made to resemble daylight with the addition of a blue filter. Duro-Test currently markets a "super-white halogen" that does the same job. I conducted a series of experiments with the Duro-Test product and found that this type of lighting does wonderful things for blue sapphire, aquamarine and amethyst, but does nothing to reduce the muddy look in blue and green tourmaline. "Super-white" induces a distinctly overblue look in rubies and tanzanite takes on an odd blue/violet multi-color effect quite dissimilar to its appearance in any other lighting environment. In diamond, "super-white" overly enhances the yellow/blue luster of the stone.

The problem!, filtered light makes for unintended results. Unfiltered fluorescent lighting can exhibit a relatively balanced spectrum when graphed on what scientists call a "Relative spectral power distribution" curve. Filtered lamps show spikes in this curve which are areas of color deficiency.

Another type of lighting called Neodymium is currently being marketed as a "full spectrum incandescent". According to Roger Schoenfeld, a lighting specialist with Durotest, this is really a standard yellowish incandescent incased in a special glass invented in Sweden, which reduces yellow and generates a spectrum richer in red and blue. Neodymium is not a bad choice. It is excellent for diamonds. Neodymium is a bit better than standard quartz for sapphire and aquamarine though not as good as "super-white". All three sources suppress the violetish to purplish secondary hue of the finer grades of sapphire.

Compared to daylight, neodymium works well with ruby, amethyst, emerald and tsavorite garnet. It is no worse with blue and green tourmaline which seems to be a true day stone, i.e. it looks its best in daylight and in daylight fluorescent 5000-6000K. Pink & red tourmalines do fine in Neodymium "full spectrum”, it does not produce the brownish secondary hue that most pinks exhibit in standard incandescent but, rather makes them look violetish. Tanzanite looks about the same as with quartz light; bluer than standard incandescent and without the otherworldly quality of "super-white".

Three or four years ago, Tailored Lighting introduced a 4700 Kelvin MR-16 lamp which has the highest Kelvin temperature of any incandescent bulb and may be the best solution yet for interior lighting. The new Solux lamp uses a new type of reflector to boost the quartz halogen lamp into the daylight range. This technology produces lighting with a fairly even power distribution curve (CRI) that shows no spikes in either the red or blue areas of the visible spectrum.

In a short, down and dirty test, Solux worked well with tourmaline, reducing the muddiness produced by all other incandescent light sources. Sapphire and ruby also benefited from this type of lamp, showing they’re colors in true daylight fashion. Solux also improved the diaphaneity of tanzanite. On the down side, Solux appeared to add a gray component to aquamarine and pink topaz which reduced the saturation and flattened the color.

Changing lighting environments have always been a problem for both buyers and sellers. You buy in one light, sell in another. Traditionally dealers who do extensive buying outside their offices have relied upon comparison stones, stones of well known color, which they carry or wear on buying trips.

I use two fixtures with twin four foot fluorescent lamps to give an overall daylight environment combined with several of the new Solux MR-16 4800K quartz halogen lamps in my own laboratory which doubles as a salesroom and consider this combination to be the closest possible to a true daylight environment. I use Duro-Test Vitalite in one fixture and Kollmorgen 6500K average daylight in the other. The use of the 6500K is to compensate for the 4800K Solux, to kick up the Kelvin temperature of the overall environment towards 5500K.

The combination of of daylight fluorescent with Solux works acceptably across the spectrum of gemstone colors. The fluorescents create an overall daylight environment and the Solux MR-16 provides the punch. This lighting temperature gives a balanced daylight color rendering when compared to New England north daylight. Several years ago, a German firm, System Eikhorst, introduced a lighting system based, in part, upon my recommendations. It includes both daylight fluorescent and Solux fixtures.

When making a purchasing decision it is important to identify the light source you are viewing the stone and to view the stone in as many lighting environments as can be found. Regardless of my geographic location at the time, I always compare each stone in daylight and 3200K incandescent to see how the stone reacts at both ends of the lighting spectrum.

If a consistent workable colored stone evaluation system is ever created, the lighting environment will of necessity be standardized. To achieve reproducible results, there are three variables; the observer, the gem observed and the lighting environment. The standardization of the lighting environment will remove one variable. This leaves one remaining variable, the observer. Either we must accept some nuances of subjectivity or build a gem grading robot replace to connoisseur’s eye and dictate our taste.

 

[Jeffrey Hunt]

I have a couple of photo examples that were acutally shot today, using Solux lighting.

Fantastic, almost colorless Australia Topaz.

Regards!

Jeffrey Hunt

 

[ooo~Shiney!]

OMG !!!!!!!!!!!!!!!!!

 

[kelpie]

Wow, there is SO MUCH to learn. I was actually practicing yesterday with my DSLR and was so disappointed with the dullness of the color compared to real life (see avatar) so I'm happy to see this very informative thread and will read it thoroughly a couple more times. Thank you!

 

[Barrett]

Yep, Jeff takes some of the finest gem pics around, in my opinion. Any tips, trick, or notes he can add should be well heard. You make a plain jane topaz look awesome. Crisp and clear

 

[Arkteia]

Amguy, hi, nice to hear from you!

I got the 3500 K from their website + the stand. As I have said, it comes in parts, something is backordered. But I read in many places that actually, you have to create "diffused" light and I now wonder how to diffuse it with minimal expenses...

 

[Richard M.]

John Betts' name has come up in this thread. He is an accomplished gem and mineral photographer who has written an excellent photography tutorial on his own website that answers many of the questions asked in this thread.

The fundamentals of camera choice, lighting set-up and other considerations are the same whether you're making images of a crystal or a faceted gem. He has provided an enormous amount of useful information for those willing to take the time to learn. Be sure to follow the page links at the bottom-left of the following pages. I think there are 4 pages in all. Good luck with your gem images!

http://www.johnbetts-fineminerals.com/jhbnyc/articles/photo.htm

Richard M.

 

[Barrett]

Hey Cras you do know the 3500K is getting close to incadescent type lighting. Any particular reason you got such a low kelvin bulb?

 

[cellentani]

Fantastic thread, amguy, and it's really nice to see you!!