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  1. #11
    Meeshoo Guest

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    Sorry Gav - can you also answer whether the Shimoyo Rubellite is heated please? The enhancement page suggests not and that it's either "natural" or "irradiated".

    Thanks

  2. #12
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    Hi Meeshoo:

    Accurate detection of irradiation and HPHT (high pressure high temperature) diamond enhancements is possible.

    Identifying irradiated colour enhanced diamonds, including greens, is a combination of several techniques including visual indicators (e.g. colour zoning, brown or green irradiation stains, etc.) and measuring the diamond’s absorption spectrum using spectrophotometers. Labs can certify ‘natural’ green diamonds without seeing the rough; it’s just that following a natural green diamond from rough to faceted makes the whole process quicker, easier and cheaper. A scan of a green colour enhanced diamond colour origin report from the EGL USA is attached for your interest. This diamond was submitted already cut.

    HPHT enhanced diamonds are detected using a combination of visual indicators (e.g. graphitised inclusions, internal cleavages, damaged surfaces, fluorescence cage, etc.) and a variety of spectroscopic clues. For example, Fourier transform spectroscopy (FTIR) and Raman spectroscopy can be used to analyse the visible and infrared absorption of suspected HPHT enhanced diamonds to detect characteristic absorption or emission lines.

    Just to reiterate, our Shimoyo Rubellite was not heated http://www.rocksandco.com/library/ge...nhancement.asp.

    Kind Regards,

    Gav
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  3. #13
    Meeshoo Guest

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    Thanks for the info Gav. Whilst it can be proven that a green diamond has been treated, it is by no means foolproof as the indicator lines suggesting irradiation may not be present. I'll detail below extracts from documents confirming that to be the case. However, more importantly, please can you answer the item in bold below:

    You haven't confirmed your earlier statement where you said "When enhanced gems are undetectable, some companies will market them as natural" - that is a pretty bold statement to make .......... as I asked earlier, please can you quantify exactly who you are referring to please? This is extremely important to gem buyers and would be of great interest to the posters on this forum I'd think.


    Green diamond certification:

    "Gem diamonds have been irradiated on a commercial basis (sometimes followed by moderate-temperature heating), to produce a range of colors (green, blue, yellow, pink, red) since the 1950s. These treated-color diamonds can often be detected by induced color concentrations that lie just beneath the facet surfaces, unusual ultraviolet fluorescence reactions and by diagnostic features seen in their absorption spectra. However, it is sometimes impossible to distinguish green and blue diamonds subjected to laboratory irradiation from those subjected to natural radiation exposure."

    Identifying synthetic and treated gem diamonds
    James E. Shigley, GIA Research, Gemological Institute of America


    Irradiated Diamonds:
    Prior to annealing, nearly all irradiated diamonds possess a characteristic absorption spectrum consisting of a fine line known as the GR1 line and an associated broad band. This is usually considered a strong indication of treatment. Subsequent annealing usually destroys this line, but may create several new ones; the most persistent of these is at 594 nm. If, however, an irradiated diamond is annealed above 1000°C, the 594 nm line is also destroyed, but leaves two new lines at 1936 and 2024 nm in the infrared. These lines are detected using spectrophotometers: the lines are best detected when the stone is cooled to very low temperatures (below -180°C).
    It should be noted that some irradiated diamonds are natural. One famous example is the Dresden Green Diamond. Naturally irradiated diamonds also possess the GR1 line.

    International Diamond Laboratories


    No fancy color diamond collection is complete without a green stone. But since, next to red, green is probably the rarest of all natural diamond hues, most collections lack representation from the green portion of the diamond rainbow. Even when they do contain greens, the stones’ color is usually not a bona fide natural one—or at least not classified as such by a gem lab of stature.

    Needless to say, this is a rather frustrating situation for connoisseurs. And it arises out of the highly ironic fact that green, while among the rarest of natural diamond colors, is the commonest of artificial ones—easily induced by alpha, electron, gamma and neutron irradiation. Yet connoisseurs spurn stones with lab-contrived color, instead dreaming of some day owning a green diamond with incontestably natural color.

    As things stand, that’s dreaming a nearly impossible dream. Since 1985, only a very few diamonds with color certified as being of natural origin have been sold at auction.

    In the past, labs were loath to validate green in diamonds as natural unless stones showed what was once thought to be a telltale indicator of natural color origin: tiny circular green and/or brown stains seen with magnification on the unpolished surfaces, called naturals, of finished stones. For instance, the 3.02-carat stone just referred to had such stains (in a girdle fracture) and was accompanied by an April 1985 GIA report with the following comment: “Color and characteristics of this stone suggest natural color.”

    Today, however, the same evidence of natural color origin would probably not be enough to merit a green diamond a comment this affirmative from GIA. Diamond graders there say that about the best such a stone can hope for at present from the school’s trade labs is to have its color origin classified as “undetermined.” While such wording may smack of fence-sitting, it is understandable since GIA feels that definitive proof—not merely educated opinion—is expected of it when making complicated color origin calls. Definite proof may be years away. In its absence, colored diamond experts think that both the gemological and connoisseur worlds must learn to live with educated opinion.

    Unlike other natural colored diamonds, the cause of color in green stones is thought to result from natural irradiation in the earth—most likely after the stones’ formation. According to current diamond color theory, some time in a diamond’s history it comes into contact with a mineral (e.g., pitchblende) containing radioactive elements such as uranium whose high-energy particles create defects in the stone’s atomic structure.

    These radiation-induced defects are, in turn, responsible for the absorption of wavelengths of red light by the diamond that result in the transmission of a complementary green color to the eye. During an examination of Germany’s famous 41-carat-plus Dresden diamond—to natural green diamonds what the Hope diamond is to natural blues—a team of three gemologists found that spectroscopic analysis of the diamond confirmed this explanation of green diamond color chemistry.

    Irradiation (coupled with heating) can produce colors such as yellow and brown that often look identical to hues produced by nature. Fortunately, these treated colors betray their lab origin by showing absorption lines that are uncharacteristic of stones with natural colors. The reason for the different spectroscope readings between other-than-green natural and treated diamonds is their different color genesis. Excepting green, natural color stems from entrapment of impurity atoms (usually nitrogen) or crystal lattice damage during the creation process while treated color results from irradiation and subsequent heating after a diamond is formed.

    On the other hand, nearly all green diamonds—natural or treated—own their color to irradiation (and, to a lesser extent, fluorescence). So whether stones are colored in the earth or in, say, a gamma cell, they will often show the same wavelength absorption lines. This doesn’t mean that experts can’t ever tell apart lab- from ground-greened diamonds. But even when they can, the job is never easy.

    Article in Modern Jeweler

  4. #14
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    Many thanks for taking the time to post all the above info Meesh, having an interest in green diamonds I find it very informative.

    You referred to the Dresden Green Diamond so I'm posting this link so that folks (who are interested) can see what a 41ct green diamond looks like for themselves. Also a bit about its background and provenance.....

    http://famousdiamonds.tripod.com/dre...endiamond.html

  5. #15
    Meeshoo Guest

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    Thanks for posting that link Sacha. Don't you think the Dresden Green looks a bit like a dinosaur egg?!!!!

  6. #16
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    Now that you mention it......it does a bit! mysmilie_1436

    Just as well it was moved in 1942 (according to the article) as Dresden was bombed to hell during the war and the diamond would likely have been lost forever.

  7. #17
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    The more I think I know the more I realise I know very little!

    Thank you Meeshoo, Sacha and others for all your very informative posts.

  8. #18
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    Hi All
    am new to the forum, correct me if i do anything wrong. Am an obsessed gem buyer, bought the ONE collection Shimoyo Rubellite necklace was on show saturday night for £9,499. Am so nervous having spent so much. Didnt receive it yet.
    Can anyone advice me regarding how much we cud spend on Rubellite any resale value at all?
    Am a medical professional
    Thanks

  9. #19
    Meeshoo Guest

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    Hi Gemlover1 and welcome to the forum. We like gem obsessed junkies on here so please feel free to share your bits and bobs! Photos are always welcome!

    You've asked a very specific question i.e. how much is Rubellite re-sale value? I'm going to be very honest if you don't mind? Buying jewellery for re-sale or investment is NOT recommended. Very rarely will you be able to recoup what you've spent for the following reasons:-

    1. Very few gemstones increase in price. There are a few exceptions but Rubellite isn't one of them (sorry).
    2. The price you have paid will be fair - even good - but how many people, especially during this economic climate, will want to spend the same on a piece of jewellery as a car?
    3. You could break the piece down into lots of different pieces but then you've got to find lots of buyers and this could take a very long time.
    4. Presuming you don't sell to a jeweller, you will then have to sell on Ebay or the like. Unfortunately, unless each piece (presuming you've broken it down) is certified you won't get top dollar.
    5. The piece I don't think is certified? Bearing that in mind, to sell it on for a decent price, a collector would demand certification.
    6. Prices for heated and treated Rubellite is less than unheated/untreated. Again, unless each gemstone is certified as such you'll struggle to sell. Gemstone junkies when paying top dollar will always look for certification or base their sale on verification of no treatments (I always do and I know others who do the same).
    7. As an indication, I bought a loose 2.71ct top quality Rubellite recently with fantastic clarity for around £150-200 (sorry can't remember the exact amount now).

    So, buying for investment is never a good idea because it will take a VERY long time for the piece to become anything more than you've paid. Buying for re-sale (if the item is low to medium cost) can work but very rarely for a substantial piece.

    My only advice is that if you DID buy it to sell on, then please make sure you have a seller BEFORE you run out of the money back guarantee period from Rocks and Co. If you haven't then send it back - don't take the risk unless you can afford to lose the £10k.

    On the plus side, if you were to get a valuation for insurance purposes, I'm pretty sure the valuation would come back as double what you've paid BUT a valuation is not an indication of worth - it's a replacement value which isn't the same thing at all.

    I do hope that helps. Please feel free to ask any questions you want.

  10. #20
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    Quote Originally Posted by Meeshoo View Post
    On the plus side, if you were to get a valuation for insurance purposes, I'm pretty sure the valuation would come back as double what you've paid BUT a valuation is not an indication of worth - it's a replacement value which isn't the same thing at all.
    How refreshing to see this Meeshoo. You would not believe the number of people who think that if they have a valuation for something and they have to claim on their insurance, then they get that amount paid out. As you quite rightly say, a valuation is NOT an indication of worth so for example, Mrs X has a piece of jewellery valued by Safeguard at £3000 and unfortunately she has it stolen, then (assuming cover was in place), the insurance company will replace the item like for like. However, Mrs X wants to replace the item herself so asks the insurance company for a cash settlement. The insurance company will NOT just pay her the valuation amount of £3000. If they agree to cash settle (and that's not always the case), then they will only pay out the amount that it would have cost them to replace the item. Therefore, with their strong connections lets say they can get the replacement item for £1000, then they'll only cash settle for £1000 irrespective of the valuation. Insurance is there to put you back in the same position you were in before the incident happened so if they can do that for £1000 why would they pay out £3000?!



         

    It annoys me when the TV Jewellery Channels go on about getting valuations for insurance purposes and people adding items to their insurance. For most of the items they sell it wouldn't be necessary as they'd be below the single article limit on the policy (if you have decent cover). They'd be better off telling people to make sure the total amount of their valuables is within their policy limits or to make sure they have accidental damage cover on their policy in case they lose a stone because without it there's no cover for that!

    Sorry I've gone off in a totally different direction from the original thread!

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