GIA colored stone grading question

[agc]

I seem to remember GIA having a color grading chart that had gem species, hue, tone and saturation. Based on this it gave a score from 0.1 to 10 with 10 being the ideal. Does this still exist? If it does still exist can anyone post it for spinels? For example, I have been wondering what is considered the ideal for a red spinel since a saturation of 6(vivid) can occur with tones of 4,5 and 6(medium light, medium and medium dark). Which order do they rank 1, 2 and 3? I realize this is not taking in to account many other important factors such as cut, clarity, fluorescence etc. I did try searching this forum but did not find what I was looking for. Thank you to all who make this forum such a great source of knowledge/information.

 

[agc]

Need TL and Chrono to help out.

Found this old link to what I am asking. Does this exist for red spinel?

GIA Grading of

I am trying to understand the colored stone grading standard of GIA and I get confused . Tone is defined from 1 to 8; 3 is light, 5 is medium, 7 is dark. Saturation is also from 1 to 8. Pink is actually red with less saturation. So for pink sapphire, is it a lighter tone red, or a lesser...

www.pricescope.com

This is from cflutist for pink sapphire below:

Let me look these up for you on the GIA Color Grading Charts:

scale 0.1 worst to 10.0 best.

R4/6 = 6.4 on a Pink Sapphire Chart

R 5/5 = 1.6 on a Ruby Chart (not listed as a Pink Sapphire)

slpR 4/6 = 6.4 on a Pink Sapphire Chart

slpR 5/5 = 1.6 on a Ruby Chart (not listed as a Pink Sapphire)

stpR 4/6 = 9.4 on a Pink Sapphire Chart

stpR 5/5 = 5.9 on a Purple Sapphire Chart

RP/PR 4/6 = 10.0 on a Pink Sapphire Chart

P 4/6 = not listed on Pink Sapphire or Purple Sapphire Chart, however P 6/6 is an 8.1 and P 5/6 is a 6.4 on the Purple Sapphire Chart, and P4/5 is 5.9 on the Pink Sapphire Chart.

Cheryl
Gemologist (GIA) 1989

 

[T L]

I’m not sure what color grading chart you’re referring to. It seems like it was a chart used a long time ago. I’m not a GG, so maybe one can comment here.

I typically go by the general GIA notations [hue tone/saturation], which is simplistic, but it gives an idea.

 

[T L]

It’s also interesting that despite the GIA teaching about the components of color, you never see gemset notation on their lab reports. You just see hue listed. AGL has a color quality report that states these variables however.

 

[agc]

Exactly. That is why when I found this old post by a GIA gemologist I wondered if this system still exists. What would be the ideal for a red spinel? Obviously, it would be saturation 6 (vivid) but vivid can be in combination with tones of 4, 5 and 6. Which is the ideal combo?

 

[Autumn in New England]

Yes! It was called GemSet. I was quite friendly with the creator, Richard Hegeman.

What Happened to the GIA GemSet Color and Hue Wheel? - Gem Society

The GIA GemSet offered plastic color masters for color grading gems. It's no longer in production. Software alternatives exist but still face limitations.

www.gemsociety.org

Now it's all electronic, and though I do not believe it is official, it's still used today. Gemwizard is another color grading software program.

What Does the GIA Colored Gem Grading Code Mean? - Gem Society

The GIA grading system describes gem color in terms of hue, tone, and saturation. Learn what the abbreviations and numbers of this gem grading code signify.

www.gemsociety.org

I find it immensely helpful when shopping a particular vendor who uses the same grading across all gems, even if subjective. To answer your question, a red spinel can absolutely be a 6 - vivid saturation and a 5 - medium tone. In fact, in my opinion, that's ideal. HTH!

 

[agc]

Thanks for the answer. Do you know what the different grades (0.1 to 10 scale) were for red spinel 4/6 vs 5/6 vs 6/6? Which got the 10 and what did the others get?

 

[Autumn in New England]

Thanks for the answer. Do you know what the different grades (0.1 to 10 scale) were for red spinel 4/6 vs 5/6 vs 6/6? Which got the 10 and what did the others get?

Do you mean tone? What we learned at the GIA was that usually, not always, you want to be in the 5-6 range (medium to medium-dark). I think this certainly holds true for most colors of spinel, including red, pink, and blue. Then we have lavenders that depart from that "rule" a bit, where a lighter tone may be considered ideal.

 

[agc]

If you have the time, look at the link in post #2. It is old but a GIA gemologist discussed a GIA color grading chart that took into account the gem species, hue, tone and saturation. Based on the tone and saturation it gave a grade between 0.1 and 10 with 10 being the best. Post #2 also shows an excerpt from that link where a stpR tone 4 and saturation 6 gets a 9.4 out of 10 on pink sapphire chart. Red with tone of 4 and saturation of 6 gets a score of 6.4 out of 10 on pink sapphire chart. RP/PR tone of 4 and saturation of 6 gets a 10.0 out of 10 on a Pink Sapphire Chart

 

[Autumn in New England]

If you have the time, look at the link in post #2. It is old but a GIA gemologist discussed a GIA color grading chart that took into account the gem species, hue, tone and saturation. Based on the tone and saturation it gave a grade between 0.1 and 10 with 10 being the best. Post #2 also shows an excerpt from that link where a stpR tone 4 and saturation 6 gets a 9.4 out of 10 on pink sapphire chart. Red with tone of 4 and saturation of 6 gets a score of 6.4 out of 10 on pink sapphire chart. RP/PR tone of 4 and saturation of 6 gets a 10.0 out of 10 on a Pink Sapphire Chart

Ahh interesting! I see what you mean now. I will definitely take a look, thank you!!

 

[agc]

I don’t know if that GIA system still exists. I would love to see how they graded red spinels or even the purple red ones.

 

[PrecisionGem]

The best grading is your own eyes, and your own taste. Buy what appeals to you.

 

[T L]

The best grading is your own eyes, and your own taste. Buy what appeals to you.

Lol, not when you’re first starting out. You should have seen the crappy stones I bought as a novice to colored gems.

Well, that’s why we have this forum.

 

[PrecisionGem]

Lol, not when you’re first starting out. You should have seen the crappy stones I bought as a novice to colored gems.

Well, that’s why we have this forum.

Maybe you bought crappy stones because you were buying cheap stones. Certainly you knew what color you liked. When you buy a pair of shoes or a car do you need to be told what the color is?
I bought a Chevy Bolt that the color is called “Shock”. It’s kind of the color of a tennis ball. Some people say it’s green, some yellow, my wife hates it and won’t drive it, I love it.

 

[T L]

Maybe you bought crappy stones because you were buying cheap stones. Certainly you knew what color you liked. When you buy a pair of shoes or a car do you need to be told what the color is?
I bought a Chevy Bolt that the color is called “Shock”. It’s kind of the color of a tennis ball. Some people say it’s green, some yellow, my wife hates it and won’t drive it, I love it.

Nah, they were pricey. I really got taken. I wish I had Pricescope when I first started collecting, but even the internet wasn’t around back then.

 

[LilAlex]

Maybe you bought crappy stones because you were buying cheap stones. Certainly you knew what color you liked. When you buy a pair of shoes or a car do you need to be told what the color is?

Nearly all colored stones are intrinsically beautiful, imo. It's only when you put them next to a much nicer one that you think, "Oh...."

There was a beautiful and glamorous Mom at the kids' school (?) or some activity and there was a fancy function where she ended up posed next to a (legit) supermodel for a media photo. Spouse took one look at that and said: "Note to self: never be photographed next to a supermodel."

And, to be fair, color is not the primary reason for buying a car. Mazda has an amazing red -- much nicer than the Chevy red, imo, but I would not buy a Mazda for that particular reason.

 

[Autumn in New England]

There was a beautiful and glamorous Mom at the kids' school (?) or some activity and there was a fancy function where she ended up posed next to a (legit) supermodel for a media photo. Spouse took one look at that and said: "Note to self: never be photographed next to a supermodel."

"I'm a 10 in Boston, but a 6 in NYC!"

 

[PrecisionGem]

My point was that many people want to judge a stone by numbers. They want to know the ratio of depth to width, table %, the numbers we are talking about here in reference to hue, tone, saturation. You can't just judge a stone by the numbers, you need to look at it. A color that may be attractive to Autumn in New England, may not be attractive to me. I know her preference in a pad sapphire is certainly not mine. Doesn't mean one is right and one is wrong.

One of the main uses of the color grading systems is for dealers to communicate color accurately to another. I think it is too easy for consumers to get lost in the numbers and never really just judge the stone with their own eyes and to their own taste.

 

[T L]

My point was that many people want to judge a stone by numbers. They want to know the ratio of depth to width, table %, the numbers we are talking about here in reference to hue, tone, saturation. You can't just judge a stone by the numbers, you need to look at it. A color that may be attractive to Autumn in New England, may not be attractive to me. I know her preference in a pad sapphire is certainly not mine. Doesn't mean one is right and one is wrong.

One of the main uses of the color grading systems is for dealers to communicate color accurately to another. I think it is too easy for consumers to get lost in the numbers and never really just judge the stone with their own eyes and to their own taste.

Point taken, but I do think education in color makes a big difference. Some stones that I thought were beautiful years ago, are meh to me now.

 

[PrecisionGem]

You should show us these early stones. It could be a good learning experience for others here. How expensive were they?

I find expensive is kind of subjective. When I first starting cutting stones, as I traveled around I would always have stones with me, and stop in jewelers and try to sell a few. One time almost 20 years ago, we were in Carmel by the Sea California. I walked to a jeweler and he bought a few stone. I was all full of my self, and stopped into another shop. The owner was very nice, told they were pretty stones, but then said he doesn't buy anything less than $40,000 for his shop. So for him $40,000 was a cheap stone.

 

[PrecisionGem]

"I'm a 10 in Boston, but a 6 in NYC!"

Now you can't say that and just post a picture of the back or your horses head!

 

[T L]

You should show us these early stones. It could be a good learning experience for others here. How expensive were they?

I find expensive is kind of subjective. When I first starting cutting stones, as I traveled around I would always have stones with me, and stop in jewelers and try to sell a few. One time almost 20 years ago, we were in Carmel by the Sea California. I walked to a jeweler and he bought a few stone. I was all full of my self, and stopped into another shop. The owner was very nice, told they were pretty stones, but then said he doesn't buy anything less than $40,000 for his shop. So for him $40,000 was a cheap stone.

I did, there’s an early thread of mine out there about my “learning stones.” I loved those gems, and now I’m like, “what was I thinking?!” I don’t remember the prices, but they weren’t cheap for what they were at the time (decades ago). I bought an expensive indicolite that was so beautiful to me, I wore it for years, then I discovered open color. I was really into tourmaline. I love bargain hunting nowadays though. I have an indicolite now that blows that one away for miles, and I paid way less per carat if I remember correctly.

However, even only ten years ago, some gems that I thought were the bomb, are kind of meh to me now.

Some of those $40k+ gems are unattractive to me, as jewelers can charge what they want. For example, I’ve seen rubies that look like pyrope, and cost thousands. However, at least you charge fair prices and you have beautiful gems. That’s why education is key. High price isn’t always condition on getting a fine gem. Some amethyst is gorgeous, but affordable, for example.

 

[Autumn in New England]

Now you can't say that and just post a picture of the back or your horses head!

 

[Voodoo Child]

And, to be fair, color is not the primary reason for buying a car. Mazda has an amazing red -- much nicer than the Chevy red, imo, but I would not buy a Mazda for that particular reason.

This. My vette could’ve been puce green with poop brown zebra stripes and I still would have bought it. Color is important, but it is not the end-all, be-all.

 

[Autumn in New England]

High price isn’t always condition on getting a fine gem. Some amethyst is gorgeous, but affordable, for example.

I'm glad you mentioned amethyst... it doesn't get enough love, IMO. It's easily one of the most beautiful purple gems and is reasonably durable. And a lot of it, contrary to popular belief, doesn't require treatment. It gets a bad name these days because so much purple quartz is heated to create citrine and prasiolite. It's also really plentiful, and therefore inexpensive. But I still love it. And the great part is you can buy large, affordable stones where the gem cutter wasn't afraid to get really creative with the faceting.

 

[LilAlex]

The owner was very nice, told they were pretty stones, but then said he doesn't buy anything less than $40,000 for his shop. So for him $40,000 was a cheap stone.

I think I know that place! The "watch guy" insulted my sapphire ring. I said, defensively, that my wife's was much prettier (although we should have just left). So she eventually made her way over and the guy squints at her ring and says "Ew, it's abraded." It ought to be after 100 years. He proudly said that he sold sapphires in the store for years before they moved him to watches. I said I could see why they moved him. He thought it was a compliment.

 

[Autumn in New England]

I think I know that place! The "watch guy" insulted my sapphire ring. I said, defensively, that my wife's was much prettier (although we should have just left). So she eventually made her way over and the guy squints at her ring and says "Ew, it's abraded." It ought to be after 100 years. He proudly said that he sold sapphires in the store for years before they moved him to watches. I said I could see why they moved him. He thought it was a compliment.

I wonder under which psychological principle he thought that was going to create a sale. I mean, that's why he's there, right? Can't just be for the snobbery? Because that's not even reverse thinking. I'm glad you got your licks in!

 

[T L]

This. My vette could’ve been puce green with poop brown zebra stripes and I still would have bought it. Color is important, but it is not the end-all, be-all.

Just like location is the most important aspect for real estate, color is considered the most important aspect of a colored gem. However, a gem is more than just its color, like the cut, luster, refractive index, size, rarity, treatment. All of these variables should be considered while looking at a gem because they work together to make something beautiful/desirable.

A car is far more important than it’s color, as that can always be changed, a good engine is a must (and that’s coming from someone that has been teen recently looking for a car).

 

[T L]

I'm glad you mentioned amethyst... it doesn't get enough love, IMO. It's easily one of the most beautiful purple gems and is reasonably durable. And a lot of it, contrary to popular belief, doesn't require treatment. It gets a bad name these days because so much purple quartz is heated to create citrine and prasiolite. It's also really plentiful, and therefore inexpensive. But I still love it. And the great part is you can buy large, affordable stones where the gem cutter wasn't afraid to get really creative with the faceting.

It used to be rare and valuable until they found enormous deposits in South America, and later Africa. The Swedish Crown Jewels has an amethyst tiara from the Napoleonic era, that was once a necklace.

The Napoleonic Amethyst Parure Tiara

Crown Princess Victoria wears the Napoleonic Amethyst Parure Tiara in Amsterdam in April 2013(Michel Porro/Getty Images) The family that currently sits on the Swedish throne has genealogical ties to Swedish kings from centuries ago, but

www.thecourtjeweller.com

Sorry to the OP to digress on tangents.

 

[Autumn in New England]

It used to be rare and valuable until they found enormous deposits in South America, and later Africa. The Swedish Crown Jewels has an amethyst tiara from the Napoleonic era, that was once a necklace.

The Napoleonic Amethyst Parure Tiara

Crown Princess Victoria wears the Napoleonic Amethyst Parure Tiara in Amsterdam in April 2013(Michel Porro/Getty Images) The family that currently sits on the Swedish throne has genealogical ties to Swedish kings from centuries ago, but

www.thecourtjeweller.com

Sorry to the OP to digress on tangents.

@Daisys and Diamonds posted about that tiara before... it's stunning!

Oh yeah, we've totally gone astray!!