Grading Tanzanite

[Tanzee]

Hi Everyone,

I just recieved an email copy of a tanzanite I bought. It was from a GG. It just seems so short there isn''t a whole lot on the appraisal. Just the weight, measurements of the stone 8x6.45x4.98mm, Color Dark,vivid violetish blue, Brilliance 45%,Claritiy TypeI/VVS, overall cut 8. This just seems so short. Should I be concerned ??

Also, I wanted a AAA+ the appraisal doesn''t mention anything at all about this, nor have I seen anything mentioned here on the boards about AAA+.

Should I be concerned with the brilliance being 45% ??

Thanks for any help

 

[Colored Gemstone Nut]

Was the appraisal issued from the company you purchased the stone from?

 

[Tanzee]

Boy oh boy it's my lucky day !!!!!

Josh I was hoping that you would respond.

I have been reading your posts since this morning!!!

No.... The stone was sent out. I had to pay $35. to have it done. I still haven't recieved the tanzanite yet because I wanted a gemologist report. Maybe I used the wrong words about who should do the appraisal and should have said something else. What do you think ???

Can't wait to hear back!!!

Thanks a lot.

 

[Sagebrush]

The best tanzanite is vivid slightly purplish blue in daylight changing to vivid purplish blue in incandescent. 45% brilliance, if by that the gemologist means that 45% of the face of the stone refracts light is poor, barely acceptable. A fine stone should be 80% brilliant.

For a good overview of quality in tanzanite Colored Stone published an excerpt (chapter on tanzanite) from Richard Wise's new book; Secrets Of the Gem Trade, The Connoisseur's Guide To Precious Gemstones. That can be accessed at www.colored-stone.com. The book website is: www.secretsofthegemtrade.com

Regards,
Dick

 

[Tanzee]

Hi there,

I just got on that sight. And I saw about hue, saturation and tone but I didn't see anything about brillance.

This is what I am talking about. I don't know what the gemologist report is ?

All that is written is Brillance 45 %

Do I have a good stone or not ?

Thanks

 

[valeria101]

----------------
On 3/20/2004 3:38:00 PM Tanzee wrote:

Hi Everyone,

8x6.45x4.98mm, Color Dark,vivid violetish blue, Brilliance 45%,Claritiy TypeI/VVS, overall cut 8. This just seems so short. Should I be concerned ??

----------------

Actually, this says very much. The guy seems to use a "shorthand" version of the GIA color grading system. He gives details on the three components of a color grade: tone (dark), hue(violetish blue), and saturation (vivid), standard clarity type (Type I) and grade (VVS), a note on cut quality and resulting brilliance. This is it!

The "AAAAAA" is actually a common commercial mark of quality, but not a standardized system. For each seller the "AAAA"-s mean a different thing.

The description you have received means that you have a stone with rarely seen fine color (the 'vivid' saturation is the most desirable, top grade) but slightly dark ('medium' or 'medium-dark' tone would have been best). The dark tone brings brilliance down despite the good cut - as expected. Also, the stone is deep - this makes the aparent color tone darker and again brings brilliance down.

About clarity: the 'Type I' means that Tanzanite can be expected to be better than eye clean in top possible clarities, the VVS grade, says that, among tanzanite, this stone has best possible clarity (free of inclusions under magnification). GIA does not, in theory, award higher clarity grades than VVS to colored gems.

The cut grade means: superior cut, with good symmetry and polish but with some room for improvement left. Given the depth of the stone, I would conclude that the cut proportions rather than execution brought this grade down. A 70%-80% depth is not uncommon in colored stones, since their lower refraction index (compared to diamond's) requires stones to be deeper in order to 'sparkle', but 77% is too much and the already saturated tone of this material would heve, most likely, benefited from less bulk under girdle.

All in all: exceptional material for tanzanite.

As an extra hunch, I would add that recutting this one would probably bring tone down to medium-dark and could improve brilliance too.

All this (and probably more, since I am not a professional and thus not experienced enough to read these grades as well as possible) IS written on the respective report

 

[Tanzee]

Ana,

Thanks so much for replying. I actually screwed up a tad on the numbers it is 8.00x6.35x4.96

I'm not sure if that is a lot or difference of not.

I guess I will just have to wait and see the stone.

But that was one of my concerns the brilliance.

What should a good tanzanites brilliance be ?

Thanks,

 

[mogok]

For anystone the brilliance is the percentage of the light that penetrate into a stone that is reflected to the eye. The cutter work is to maximise the beauty of the stone. It is in technical words to maximise the brilliance , the color of the stone, and to make it as clean as possible from inclusions as these inclusions can disturb the light travel whithin the stone.
The brilliance is the percentage of light entering the stone that comes back to the eye. In the case of your stone it means that 45% of the ligh will come back. It means that your stone have probably a window (cantal area in the center of the stone in which the ligh goes through the stone) and/or extinction (areas in which the light from the top go through and no ligh come from under).
45% is not really good if the cut is you main concenr in a gemstone. But it can be a nice stone anyway... Its a question of taste. In market like Germany, Switzerland, Japan (Engeneer countries): Cut is the first concern about a gemstone. In Many other traditional markets: France, Italy, Middle east, India (More artictic countries... (Hum?!))Color comes first...
On a general term:

No stone is bad if you like it!

And you can still have the possibility to recut your stone if you want to make it more brilliant...
All the best,

 

[valeria101]

300% agreed with Mogok - you have to see the thing. The new numbers make the piece even deeper, to the point where I would start wandering. I believe that this 45% is ok for a dark stone, but not a show stopper otherwise.

I must say that I am not a believer in thie system of comunicating light return by percentage points. It is useful, but it says little about the appearence of the stone. These are not diamonds, so brilliance has to be judged along with color somehow. I would consider 70% to be exceptional - in this system.

The dark tone would be more of a concern to me, not brilliance. Chances are that this stone would appear overly dark once mounted - not great news.

 

[Colored Gemstone Nut]

Brilliance can also be described as internal luster and can be a significant contributor to a gems beauty and appeal. Brilliancy also tells us much about a gems cut as well as how internal characteristic’s may be diffusing light transmitted through the crystal and can provide a look into the gems tone and saturation. When you rock your gem back and forth you might observe flashes of brilliancy trading places with similar areas of extinction (areas with no flash). In grading a mental estimation is taken of the total area of brilliance & extinction as a percentage. Like Mogok & Val mention cutting plays a big factor in how light is also viewed through the crown and can improve brillance dramatically based on the level of cutting. A good cutter will try to maximize all the attributes which give a gem it’s beauty.

 

[Tanzee]

Thank you, Thank you, Thank you,

I am planning on having this stone set into a ring.

I thought when you were looking for tanzanite you should look for color.

Do you think that the stone will be way to dark once mounted into a setting ? With no brilliance ?

I know nothing at all as you can tell.

If I put into a setting with some small diamonds around it would that help ?

What do you suggest ?

Thanks for all your help and comments, the more the better!!!

 

[Colored Gemstone Nut]

I thought when you were looking for tanzanite you should look for color.

Do you think that the stone will be way to dark once mounted into a setting ? With no brilliance ?

I know nothing at all as you can tell.

If I put into a setting with some small diamonds around it would that help ?

What do you suggest ?

Thanks for all your help and comments, the more the better!!!


----------------

When shopping saturation of color is important, but when a stone is too dark it will not maximize the stones color especially when set. When you get your stone set if it is too dark for your liking you can have a cutter take a look and give you an assessment on what can be done..

 

[valeria101]

Best tanzanite color would read "medium or medium dark violet-blue, vivid saturation". If you want to focus on color (and I could not agree more with this), this is not it. The only kind of setting that would help a stone look less dark is one... with a small bulb in it

However, this is THEORY: I have not seen the stone. It could be very nice and I could love it too. It is just the general rule of thumb that 'dark' tone is too dark. Vivid saturation even in a dark stone would most likely make the areas with poor light return at any given time look a deep blue rather than black and will certainly help brilliance deliver some lively color flash. Who knows what this one looks like? Can you see the stone before buyin it? Is there a return policy?

 

[Tanzee]

How small than do you think the stone will then become ?

 

[valeria101]

----------------
On 3/21/2004 12:01:58 PM Tanzee wrote:

How small than do you think the stone will then become ?----------------

We know so little about it! No way to tell. I suppose the size (length and width, or face-up surface) of the piece could remain virtually the same while the pavilion is recut. So the weight may go down with an indeterminate amount while size remains the same. You can, most of the times, choose how radical you want the recutting to be. Usually, some improvement is possible without severe weight loss. Changing the cut model causes the most weight loss: so a a light retouch could be very different than getting concave faceting or more radical such moves.

All in all, buying a gem for recutting should be a personal decission by all means: you will pay a price per carat for the initial piece, than pay for recutting and obtain a lighter gem (even if the size could remain the same). This could still keep the final price competitive, it is all in your hands

I should say that, more often, gems are recut to improve the symmetry face-up than to improve brilliance (which requires recutting the pavilion). The first procedure is quite 'cosmetic' - it does not affect size and takes away little weight, the second may affect size and is usualy expected to reduce weight considerably. This really is one thing the cutter should tell you with stone in hand. The appraiser could also give a better view on recutting given that he handled the piece.

 

[Tanzee]

Yes I did see the stone, only over the internet. He took different pics for me and it did look good. But that is why I had him send it to a gemologist to get a report.

And yes I can return it, but I'm not sure about getting my money back for the gemologist report. I had to pay $35. for that.

Thanks for all the input. I guess I will just wait till I see the stone. I didn't realize that once you set it, that it will look darker in the setting.

Thank you all....... Very much!!!!!!

 

[elmo]

Nicely colored, well cut tanzanite is common enough in the market in a variety of sizes over 4-5 carats that't I'd be hesitant to buy one that isn't pretty nice all around, including well cut. If you tell your jeweler that's important I'd be surprised if he couldn't come up with several to choose from.