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Mandarin Garnet -- it's a crap shoot

Discussion in 'Colored Gemstones' started by Upgradable, Aug 29, 2011.

  1. Upgradable
    Ideal_Rock

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    by Upgradable » Aug 29, 2011
    I know you usually get just what you pay for, and understanding this I stumbled across this on ebay and won it on a very low bid. Is is presented as being a 3.32 Mandarin Spess Garnet from Namibia. I bought from Siamgold78, whitch has 100% rating. Now I just have to wait for it to arrive and see what I got.

    Even though I've already bought, I'd love to hear your thoughts and opinions. It can always go back, and for the price I was willing to take the risk!

    spess1.jpg

    spess2.jpg

    spess3.jpg

    spess4.jpg
     
    


    


  2. natsplat
    Brilliant_Rock

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    by natsplat » Aug 29, 2011
    I'm absolutely sure I'm very stupid as regards top-level colour etcetc, but I think it's blummin' GORGEOUS :love: It looks so saturated, and the cut is fab. It may be Photoshop, but I can't wait to see if it is an realistic representation...! :appl:
     
  3. colorluvr
    Brilliant_Rock

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    by colorluvr » Aug 29, 2011
    I've had good luck with Siamgold78's stones. Like many, her photos are flattering, but I don't think they are photoshopped. Only problem I've had is the stones are sometimes darker than the photo due to her photographer using bright studio lights. She's great on returns if for some reason you don't like the stone.
     
  4. chrono
    Super_Ideal_Rock

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    by chrono » Aug 29, 2011
    Tweezers look pretty bright but you are being cautious, so I think your expectations are in-line. Probably darker in person with some brown but as you said, you didn't pay a lot for it. It might still be worth more than what you paid for it.
     
    


    


  5. T L
    Super_Ideal_Rock

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    by T L » Aug 29, 2011
    Mandarin garnets are almost always photoshopped on ebay to look more orange than they really are. I suspect it will be browner and more "citrine" color than a true bright neon orange color. Good luck, I hope it meets your expectations.
     
  6. Arkteia
    Ideal_Rock

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    by Arkteia » Aug 29, 2011
    Uppy, I am always very adroit so I have to tell you about my experience with Siamgold. I am not saying he is a bad vendor - in fact, PS once rated him highly. And what I am going to write is not a fact, just my opinion, but I'd check large stones I buy from him. He is on my list of saved vendors, but with "trust but verify" mark.

    I once bought a couple of very small spessartites as side stones. The price was excellent and the delivery fast, the stones not what I expected, too brown-reddish but OK. But... I once bought a larger colored CZ from another vendor and something in these small stones resembles me that colored CZ. Too sparkly. Again, I can not accuse someone since I never checked the RI, just accepted very cheap stones, and they are too cheap to even bother. I gave him a positive review, but I did notice on the Toolhaus that someone checked his stones and found out they were CZs. Again, it might have been a hostile buyer, but most people purchase small cheap stones never worth checking so who knows...

    I think that your situation is different, since you bought a large stone, and I am positive he does not photoshop his pictures that much. And the stone is beautiful and saturated.

    Perhaps I should not even have mentioned mine, but ebay is a minefield.
     
  7. PrecisionGem
    Brilliant_Rock
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    by PrecisionGem » Aug 29, 2011
    Can we ask what you paid of it? If it looks like the picture, the stone should easily sell for over $1000.

    Spessartite can be a bit tricky to ID with a refractometer, since the refractive index is usually above what can be read, and so is CZ's
     
  8. Upgradable
    Ideal_Rock

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    by Upgradable » Aug 29, 2011
    Gene, I paid no where near that!

    Crasru, I appreciate you sharing your experience. Those are the important pieces of info that I count on from my PS pals.

    Chrono and TL, we'll see how well represented the vendor pics are when I receive the stone. You can be sure I'll share the pics here.
     
  9. colorluvr
    Brilliant_Rock

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    by colorluvr » Aug 29, 2011
    Did you buy from Siamgold or Siamgold78? I'm asking because I didn't see that negative feedback for Siamgold78 on toolhaus. The owner of Siamgold78 (or at least the person that I always conversed with) is a woman (at least I think so) and her name is Mai. Most of the stones that I have purchased from her have certs. Not saying that didn't happen to you, just wondering if is is the same seller as the one Uppy and I bought from.
     
  10. LisaRN
    Ideal_Rock

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    by LisaRN » Aug 29, 2011
    I hope it is lovely like the picture. Word of caution - I just bought a spinel from a US ebay seller with 100% glowing feedback. The stone was chipped, fractured and had an RI of 1.73 and when I put in under a blue UV light it flouresced green. I asked to send it back and the seller went nuts on me. Told me his "well respected source" and this turned out to be a Thai seller with 689 negatives on Toolhaus. From now on only reputable sellers with known reputations for me. But if you can snag a deal - that is always great fun.
     
    


    


  11. Pandora II
    Ideal_Rock

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    by Pandora II » Aug 29, 2011
    I'm with Gene on this one.

    If the colour is accurate and it's also clean and well cut, this should be a pretty expensive stone. If it's not then there is a reason.

    If it does look that colour them I'm trying to think if there is a way to ID a spess with minimal equipment (refractometer is of no use) and since both garnets and CZ are both isotropic a polariscope isn't going to help either, plus both have high lustre. Best best will probably be to see what there is in the way of inclusions. If it's super-clean then be very suspicious.

    (There was something I read about spess and magnets - will have to have a look but I think they were a certain type (?), anyway that could be a possibility)
     
  12. zeolite
    Brilliant_Rock

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    by zeolite » Aug 29, 2011
    If it's a true Mandarin, should have many 100's of tiny inclusions at 10X, vs none in CZ. Also Spessartite has a specific gravity of 4.1 vs 5.7 for CZ. A 3.32 ct size stone specific gravity should easily calculated on a balance scale, measuring in and out of water.

    FInally, we know the weight of the gem at 3.32: Try this formula:

    L x W x D x 4.1 x .0017 (shape factor) = 3.32 cts. If the weight is much more ( 5.7/ 4.1 * 3.32 cts) = 4.62 cts, is probably a CZ. If the weight is correct and it is a CZ, then the L W D must be much smaller in this formula to weigh 3.32 on a scale , as this formula will show.
     
  13. Arkteia
    Ideal_Rock

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    by Arkteia » Aug 29, 2011
    Colorluvr - it was such a long time ago that I can not figure out. I have absolutely no documentation left. So since I may be saying derogatory things about the wrong person, I should ask the mods to remove my post so that it does not shed a light on a person who may have nothing to do with my stones. It is concerning, though, that there are so many "clones" on ebay. Recently I saw "gem-cave"...
    Please pay attention, though, that I gave a positive review to the person. Why? Because reviews are so generic. Did it arrive on time? Was the item as described? Etc, etc. So unless you are really sold on proving that someone sold an imitation, you just click 5 stars... No one would bother for a pair of small cheapos. Unless it is a person with gemological background who is buying for a reason, not like me.
    I always check NEGATIVES. There


    Mr. Zeolite - it is GREAT! THANK YOU, THANK YOU, THANK YOU! :appl: I have two more spessartites which I have doubts about - the cuts are wonderful but they are too beautifully yellow and too clean, now at least I can try to check weights/SGs! I wanted to either use one for the project or sell both but did not feel comfortable selling something that might be imitation (I think CZ can be called imitation in this situation). Now at least I shall feel more comfortable.

    What is a shape factor? Does it vary depending on the shape/cut, e.g., for round, cushion, and other cuts?
     
  14. Richard M.
    Brilliant_Rock
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    by Richard M. » Aug 29, 2011
    I have several spessartites that are optically clean at 10X so I think judging by lack of inclusions could be misleading. A manganese spectroscopic signature could indicate a genuine spess although I hasten to note that I don't know what the chromophore is in orange CZ.

    I think the high S.G. of CZ would be a very useful test, as mentioned by Mr. Zeolite. Spessartite is magnetic but a very strong rare earth magnet is needed for testing. That might be a valid test because most CZ colors (pink excepted) are inert or show a weak response.

    Richard M. (Rick Martin)
     
  15. Upgradable
    Ideal_Rock

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    by Upgradable » Aug 29, 2011
    Mr. Z, you just made my head spin so fast that it disconnected!! If I give you the measurements, could you calculate for me?

    The dimensions are 9.04 x 8.12 x 5.67 mm, and it weighs 3.32. It has a cert from BGL, but I don't know what that's worth?
     
    


    


  16. zeolite
    Brilliant_Rock

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    by zeolite » Aug 29, 2011
    Shape factor for pear = .0016, round=.0018, oval =.0020, emerald cut = .0025. I had to guess the shape for a heart; somewhat less than round. This is taught in your gemology lessons.

    A brief math lesson: the circumference (C) of a circle is related to the radius (R), but it is not equal to the radius. A constant (an unchanging number) can change a relation into an equation: C = 2 pi R (where pi = 3.14159...).

    A shape factor, which is experimentally determined, can give you a constant which can be used in my formula to calculate the actual weight.

    People interchange the terms density and specific gravity, which are not quite correct. Density must have units (gm/cm2), whereas specific gravity is the ratio of the weight of a material to an equal volume of water. The units (numerator and denominator) divide out (cancel), so it has no units.

    Using the balance scale, the specific gravity = weight in air /(loss of weight in water) = weight in air/ (weight in air - weight in water)
     
  17. Upgradable
    Ideal_Rock

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    by Upgradable » Aug 29, 2011
    Mr. Z, you're killing me here!!! :errrr:
     
  18. zeolite
    Brilliant_Rock

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    by zeolite » Aug 29, 2011
    This won't help you, but here goes:
    9.04 x 8.12 x 5.67 x SG x .0017 = 3.32

    .7075 X SG = 3.32

    SG = 4.692

    Unfortunately that SG specific gravity is in between the density of spessartite and CZ. The scale, weighing in air and water, will give you better accuracy than my formula.
     
  19. Upgradable
    Ideal_Rock

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    by Upgradable » Aug 29, 2011
    I finally "got it"! Thank you for giving me Gem ID for Dummies. :wacko:
     
  20. zeolite
    Brilliant_Rock

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    by zeolite » Aug 29, 2011
    Shape factors may not be completely accurate, because one cutter could cut a heart with a very straight sided pavilion, while another cutter could cut the same size gem with a very bulging pavilion.

    Gem cutters who are very precise and repeatable, can calculate a very accurate shape factor, by just cutting a stone, and plugging in all of the dimensions, specific gravity, the weight, and calculate the shape factor for HIS style of heart cut. Then, the next time, his shape factor is VERY accurate.
     
  21. Arkteia
    Ideal_Rock

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    by Arkteia » Aug 29, 2011
    The difference in the shape factors should matter only if the difference between the calculated and the real weight is small. If it is large, it may not be so relevant.

    Thank you, Mr. Z., it is very interesting!

    But, the weight is what the seller says it is because Uppy has not received the stone yet. It may be less, hardly larger though :bigsmile:

    If it is less, then the SG becomes closer to that of the spessartite.
     
  22. zeolite
    Brilliant_Rock

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    by zeolite » Aug 29, 2011
    Density must have units (gm/cm2) argg!

    Should be gm/cm3
     
  23. PrecisionGem
    Brilliant_Rock
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    by PrecisionGem » Aug 29, 2011
    It's hard to use shape factors to determine an accurate weight, since so much is effected by the cutting; height of the crown etc. The stone is large enough that with decent equipment you should be able to get a pretty accurate SG. Once you handle a lot of stones, a CZ sort of stands out in your had as being too heavy.

    Another possibility could be lab created sapphire. If that's the case, than a simple refractive index measurement will expose that.

    I have yet to run into any dealer that doesn't have a clue what things are worth, and would be willing to sell a $1000 stone for $100. When someone posts an eBay auction with a $.99 starting bid you really need to wonder would someone be willing to risk the stone (or other item) being sold for just $0.99

    I don't know what the opening bid was, or what you paid for the stone, but generally, if a deal sounds too good to be true, it most likely isn't true. But you never know....
     
  24. pregcurious
    Ideal_Rock

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    by pregcurious » Aug 29, 2011
    Hmm, I wish we PSers had the option of pooling our resources to randomly check the ID of inexpensive stones. For example, we all enter a lottery to have our stone with less than $100 value to be checked. Everyone buys a "ticket", but one stone gets picked and tested and the results are shared on PS. It would be like the Consumer Reports of CS.
     
  25. Arkteia
    Ideal_Rock

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    by Arkteia » Aug 30, 2011
    On a totally different note - how can a vendor have a 100% rating? Especially if one has sold several thousand items? Shouldn't there be ONE unhappy customer? ONE person who does not want to pay for shipment back to Thailand? One person with a headache? ONE bitchy person, at least? Statistically, how come all 740 people are happy with their purchases?

    Tan does not have 100%, and I am positive that our best vendors here have their share of returns... How can it be a 100%?

    I'd not look at this system any longer, just at the negatives at the Toolhaus.org. And not just how many negatives, but what is said there. If someone got his stone later than expected, it may not be a negative. If it is a synthetic stone, it is a negative.
     
  26. Pandora II
    Ideal_Rock

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    by Pandora II » Aug 30, 2011
    Ah, I was going more on the 'if the stone is this good a colour and the price is cheap then something has to give somewhere' premise. Premium colour + no inclusions + great price = something is potentially up.

    I'd agree that the SG test is probably the best - but is it likely that someone will have a set of sufficiently accurate scales or any of the other bits and bobs just lying round the house? Ditto with a spectroscope...
     
  27. Upgradable
    Ideal_Rock

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    by Upgradable » Aug 30, 2011
    I'm quite embarrassed to say that I don't think any of my local jewelers has the equipment to ID stones. I guess I could call around into Oklahoma City and see who could do this. Based on the cost of this stone, I don't want to send it out for appraisal until I at least know that it is natural.
     
  28. Arkteia
    Ideal_Rock

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    by Arkteia » Aug 30, 2011
    Any decent appraiser could measure and weigh the stones. Mine had to go an extra mile with my first colored CZ to prove that it was a CZ but he did not even charge me because he said that it was a learning experience for him as well. I do not expect these tests to cost too much in Oklahoma City but I'd first wait till the stone comes. We do not know how it looks IRL.
     
  29. bobsiv
    Rough_Rock
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    by bobsiv » Aug 30, 2011
    I just bought a small rare earth magnet for like $.50. And I just cut a red-orange Nigerian Spess that the magnet will actually pick up.
     
  30. Upgradable
    Ideal_Rock

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    by Upgradable » Aug 30, 2011
    Wow, that is amazing! Where can one get a "rare earth" magnet?
     

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