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New to coloured gemstone buying? Read this first!

Discussion in 'Colored Stones' started by LD, Apr 15, 2012.

  1. LD
    Ideal_Rock

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    by LD » Apr 15, 2012
    First of all welcome to our technicolour world! :wavey:

    If you've never bought coloured gemstones before, you're in for a real ride and I'm hoping that this thread may help you on your quest for your "special" one! One thing it's important to know .......... this part of PS is frequented by gemstone lovers from vendors to collectors to enthusiasts to newbies! At the end of the day, we all have opinions/likes/dislikes but ultimately you must buy what you LOVE, not what others tell you to buy! Also, don't chase the "gemstone of the month"! Typically there are trends on this board, Mahenge Spinel for a few months, followed by Spessartite Garnets, then onto Sapphires etc., but running with the pack can be boring. Don't buy because something is flavour of the month - buy because you'll wear and love it!

    Believe it or not, jewellers in your neighbourhood (with some exceptions of course) very rarely have the specialised knowledge that you'll find on this forum. If a jeweller hasn't run tests on a gem and says "that's an X stone" then my advice is to take that with a pinch of salt. In order to verify what a stone is you normally have to run a battery of tests - some can be done by jewellers such as testing the RI (Refractive Index) of a stone - sometimes can be done with mounted stones but not always - but some tests really have to be conducted by a laboratory. You wouldn't let somebody tell you you had a blood disease without a blood test would you? It's the same thing!

    Why is it different from buying diamonds?

    If you buy diamonds - forget everything you've learned! Buying coloured gemstones is a whole different ball game. For example, when you buy diamonds, you can evaluate performance (or get a good idea) by looking at statistics, depth, girdle, table etc and by looking at scans. You can't buy coloured gemstones purely on numbers. In fact, you've already got the tools you need - YOUR EYES! Generally speaking, coloured gemstones are valued by colour first - clarity is not such an issue (more about this later)

    Colour/Cut

    So, colour is king! Generally speaking the more vivid a gem appears, the more valuable it is. You will see words like "tone", "hue" and "saturation" used. A table below shows what these mean and I find this visual representation good because it's something I can remember! The table below shows the colour blue but the same is true for other colours! Interestingly, a pure stoplight red is one of the most valuable colours for a gemstone and is very rare. Finding a pure red stone is probably the most difficult search! However, you may prefer lighter tones or less saturated gemstones. If you do that's fine and lucky you because actually that means you'll be paying less! Every cloud has a silver lining!

    There's a bit more about this on this link you may find interesting - it's quite basic so not to traumatic to read: http://www.swissgemlab.com/EducationPages/EducationDetailPage.aspx?pcid=332&AspxAutoDetectCookieSupport=1

    Cut:

    Another word you may see when discussing colour or performance is "extinction". Extinction is basically when a gemstone has lots of "black" areas - when you move the gemstone around some parts will remain black and NOTHING you do will make that change. If a gemstone has been cut so that it has extinction, it'll always have extinction! See the second photo below and here's a link that discusses it in great, easily to understand, detail: http://www.ruby-sapphire.com/brilliance_windows_extinction.htm

    So what's a "window"? Well a window is when a gemstone has been cut (typically) very shallow. What you'll see is a part in the centre of the gemstone that appears to lighten or even lose all of its colour. In effect it's a window and you can see through it! Why's that bad? Well, it means the colour is not being reflected back to your eye so it's negatively impacting on the performance of the gemstone. Small windows can be disguised by using a setting that has a more enclosed basket under the gemstone (in effect it acts as a mirror that helps to reflect the light back to you). But be aware that not all settings will do this and not all windows will close. An example of gemstones with windows is in photo 3 below.

    Often I see somebody say "should I buy this and then have it recut"? My advise is always not to unless you (a) really know what you're doing or (b) have been in touch with a cutter who has evaluated the stone and thinks a recut may be possible. This is a skill in itself and not for the faint hearted. If you do recut a stone, please be aware that it may dramatically alter the stones appearance and it may not be for the best! Also bear in mind, some of the most valuable gemstones on earth have been cut to preserve weight and so may be windowed but don't be put off buying them because you could be missing out on a real bargain!

    Should I buy a "precision" cut gemstone or a "native" cut one and what's the difference? Well, this is a personal preference. Precision cut gemstones are exactly what they say on the tin and they will be cut to maximise performance. If you will only settle for perfection then this is the route for you! However, precision cut gemstones are a smaller portion of what's available on the market. The majority of coloured gemstones are not cut to precision. You will sometimes see these termed as "native" cut stones. This terminology can sound derogatory but think of it as meaning "not precision". There are native cut stones and then native cut stones! Some are cut so wonkily that you'll need to balance on one leg and tilt you head to one side with one eye closed to make the gemstone look straight! Clearly the value in such a gem will be less than one that is more pleasing to the eye. There are a large number of collectors who don't mind buying native cut stones because there are some quite beautiful ones. The most important thing is that you buy what YOU love and what appeals to you. Precision cut or native cut it doesn't matter!

    Inclusions

    Inclusions can be a good thing (believe it or not)! They can sometimes verify that you've got a natural gemstone and not a synthetic or lab created gem. However, there's a difference between a few inclusions and then inclusions that take over the whole stone and affect the overall beauty! "silk" is a really good example of this. Some gemstones have rutile type inclusions that make the gem look silky or hazy. It can, in some gems, make them glow incredibly! In other cases it can make a gem look murky and in need of a good clean! Unfortunately, you can't clean out internal inclusions so don't make the mistake of buying and thinking a good rub with a cloth will sort it out - it won't! Inclusions can be fascinating or they can be incredibly annoying. Again, judge what's acceptable to you.

    Very few gemstones are flawless. In fact, gemstones are often listed as "types". Some gemstones are type 1, some type 2 etc. The type refers to whether they are naturally included or not. This website has a list of gemstones and what category they fall into. It's important you read this so you know what's "typical" for your chosen gem. http://www.multicolour.com/catalogue/columns/column01003.html

    Durability

    Surprisingly, not all gemstones are suitable for every day wear. The only ones that are considered durable enough are diamond, ruby, sapphire, alexandrite, chyrsoberyl and spinel. Most others, for one reason or another, are more prone to damage by frequent wear. Durability is not just about hardness but it's about the chemical make up of the gemstone i.e. the cleavage. If you knock some gemstones in the right place, you can split them completely in half - a bonus is you'll have a pair of earrings but it may be an expensive accident.

    Make sure you research the gemstone you love. If it's lower down the MOHS scale then it's less durable and more prone to scratching, chipping and pitting. Generally, don't get gemstones near water, don't do the gardening in them, think before you change a tyre on your car and know how to clean them properly! However, if you know how to take care of your chosen gemstone then don't be frightened to buy what you like. There are many examples of people who have worn Emeralds (a softer, more brittle stone than a sapphire) for years without a problem and then others who have one for 6 months and have damaged it beyond repair.

    Carat weight/Size

    Is weight important? Well carat weight can certainly be important. For most gemstones, over 1ct is good. For rare gemstones such as Paraiba Tourmaline, Alexandrite, natural Rubies etc., the size of the gemstone can be phenomenally important. In more easily obtainable gemstones it's a nice to have!

    Now then, we come to THE most important thing for you to know about when buying coloured gemstones! TREATMENTS!

    Treatments

    If you buy a Rolls Royce you expect a Rolls Royce don't you? You'd be really fed up if you found that you'd bought a Skoda in a Rolls Royce wrapping wouldn't you AND you'd paid Rolls Royce prices? Well, that's why treatments are important for you to understand. Again, this is personal. Some will accept only natural gemstones, others will accept some but not all treatments, others just don't care and want a sparkly gemstone! Who's right? Everybody! It's a personal thing again! You need to do your own research because treatments affect buying prices and values of gemstones so it's probably the key thing to deciding if you've paid a fair price.

    I can't cover all treatments here but here's a few and you can always do internet searches for more information if you want to research in more detail. BE AWARE, NOT ALL TREATMENTS ARE DISCLOSED! YOU MUST ASK AND THEN VERIFY WITH A LAB REPORT IF YOU'RE BUYING AN EXPENSIVE GEMSTONE:-

    Natural and untreated - gemstones are mined, cut and sold exactly as nature intended them to be! They are exactly as it says on the tin - natural. They are usually the most expensive type of gemstone and most difficult to find. Some gemstones are never or very rarely treated and so this is expected. Research your chosen gemstone to see if yours is one that is normally left alone!

    Heated - Some gemstones are heated in the Earth naturally and it affects their colour, changing them from one colour to another. For example, Tanzanite is naturally a brown muddy looking gem but some, heated by the earth, comes out of the ground in a beautiful blue or purple, green or orange etc. Some gemstones are heated routinely and this is accepted. So, for example, if Tanzanite comes out of the ground brown, it's heated by man and becomes a gorgeous blue. 90% of all Tanzanite is heated in this way so it doesn't affect the price. Other gemstones like Ruby for example, is heated to improve appearance by lightening and making inclusions less visible. A heated gemstone (with the exception of gems that are nearly always heated) will be expensive but not as expensive as a natural untreated gemstone.

    Oiling - Most commonly you see this term used when discussing Emeralds. Oiling goes back to Egyptian times and it's a way of infusing inclusions in Emeralds ("jardin") with an oil to make them less visible and the gem more beautiful. There are different types of oils and if you buy an Emerald in particular it's useful to know what oil or treatment has been applied because oil can dry out and make need to be re-done.

    Now we come onto those treatments that are a bit more contraversial!

    Fracture filling/Dyeing - Some gemstones have their inclusions filled. This treatment is not necessarily stable and putting a gemstone into a sonic cleaner can cause the gemstone to spit out the treatment leaving you with a very very ugly gemstone. Rubies and sapphires are often filled with glass, lead, and are even sometimes dyed. Is this acceptable? Well, again it's personal preference. This does affect the value/worth of the gem and therefore if you buy a gem that's been treated in this way, please make sure that you're not paying too much.

    Irradiation - Some gemstones are irradiated to improve/change colour or appearance. For some it affects value (for example a coloured diamond) for others it doesn't i.e. some tourmalines are irradiated. Leaving aside coloured diamonds for a minute, in some cases this treatment isn't detectable but it is stable.

    Berilium or Lattice Diffusion - Years ago, it was discovered that adding an element into the heating process with the gemstones could actually change the colour of the gem to make it far more pleasing to look at. When this process first hit the market it only covered the surface of the gemstone so if you chipped the stone, you would see a different colour underneath! Technology has moved on and now diffusion goes right through the gemstone so even if it were to be cut, you'd see the same colour throughout. Is this a natural gemstone? Well, yes but it's a natural gemstone that has been artificially changed by man so that it's more acceptable. Typically these stones don't have much value but can look very beautiful. If you're looking for a cheap sapphire (for example) then some of the loveliest most affordable colours are diffused. Please be aware that these will not be heirloom pieces and so you shouldn't pay much for these.

    Coatings - Gemstones like Topaz are commonly coated. You can find some diamonds that have been coated also. The problem with coatings are that if you scratch the gem, the coating will come off. It's not too much of a problem if you've bought an inexpensive topaz but imagine if you've bought a pink diamond thinking it's natural, scratch it and then off comes the colour!? Not good.

    Verifying what you've bought

    Unfortunately there are quite a few gem sellers who will not disclose treatments and this means that you could buy a gemstone for a high price when it's actually worth less. This forum has a section that has vendors commonly used by frequent posters on this board and they're named on there because they are honest sellers (some of whom frequent this board) so if you're really worried then look at what they have to offer before venturing into the world of sharks that is Ebay!

    For coloured gemstones, lab reports are valuable because they will verify that you have (a) bought the gemstone you thought you were buying and not a synthetic (b) the size (c) sometimes colour will be graded (d) location if it can be proved and if you've asked for that to be included. What a lab report won't do is put a value on your gemstone. Generally speaking if you're in the US, AGL is the lab to go to for coloured gemstones. In Europe it's either Gubelin, GRS or AIGS.

    So, do some research but remember, buy what you like and what's right for you might not be right for the next person but will be loved by others! Happy gemstone buying!

    I'm sure I've missed some key points so follow posters, please jump in and add info!

    Tone and Saturation.jpg

    Extinction in gemstone1.jpg

    Windowing2.jpg
     
  2. slg47
    Ideal_Rock

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    by slg47 » Apr 15, 2012
    LD, fabulous post!!! :appl: :appl: :appl:
     
  3. diamondringlover
    Ideal_Rock

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  4. minousbijoux
    Super_Ideal_Rock

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    by minousbijoux » Apr 15, 2012
    Thank you for taking the time to write this all out - so many of a newcomers questions will be answered if they read this. I assume it will become a pinned thread. Thank you so much!
     
  5. Enerchi
    Super_Ideal_Rock

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    by Enerchi » Apr 15, 2012
    Fantastic wealth of information all wrapped up neatly in a perfect package! Thank you LD! :appl:

    (hopefully the mods will see this and make it a pinned thread on CS)
     
  6. Starzin
    Brilliant_Rock

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    by Starzin » Apr 16, 2012
    Well done LD! :appl:

    This is an invaluable "in a nutshell" for newcomers and I truly think it should be required reading before posting in the CS forum - might save you, TL and a few others from having to repeat some information over and over. Someone coming to PS for advice may read one pinned thread such as this but won't research the forum because (often) they don't know what they need to know.

    Another request for mods to please pin this!
     
  7. Ella
    Administrator
    Staff Member

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    by Ella » Apr 16, 2012
    Starzin, it is already pinned. :))
     
  8. Starzin
    Brilliant_Rock

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    by Starzin » Apr 16, 2012
    Thanks Ella! :))

    Didn't refresh did I :roll:
     
  9. missy
    Super_Ideal_Rock

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    by missy » Apr 16, 2012
    Wow LD, thank you so much for this thread! I know nothing about colored gemstones but love them and am so glad to have this thread (and forum) as a reference.

    When my dh and I were on our honeymoon in Italy (way before I discovered PS unfortunately) we foolishly bought a very expensive diamond aquamarine ring which has a huge window that I obviously didn't realize at the time. I was just in lala land during our honeymoon and fell in love with a very defective ring. So glad you started this thread to help other newbies not make the same mistake!
     
  10. PrecisionGem
    Brilliant_Rock
    Trade

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    by PrecisionGem » Apr 16, 2012
    Fantastic clear, well written post LD.

    Could I use this on my website? I'd give you the credits for it of course.
     
  11. LD
    Ideal_Rock

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    by LD » Apr 16, 2012
    Yes of course Gene, I'd be honoured! I wrote it at speed yesterday and on reflection I've missed bits and could include a few more things. So please feel free to add/delete as you feel appropriate.

    Dear All - thank you for your kind comments. I do hope that this assists somebody new to coloured gemstones to get the best from their purchases and make informed decisions.

    If anybody thinks something has been omitted - please do add to this thread.
     
  12. chrono
    Super_Ideal_Rock

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    by chrono » Apr 16, 2012
    Great write up, LD. This is a good read for everyone new and old to PS so nobody has to rehash the same answers time and again. :appl:
     
  13. ChrisA222
    Brilliant_Rock
    Trade

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    by ChrisA222 » Apr 17, 2012
    LD, this is great. I thought of a couple of other segments that maybe can be added. I really don't feel comfortable doing it myself, as I know my knowlege is far surpassed by many on this forum. Perhaps we could add:

    Brilliancy, what does it mean? How is a stones Refractive Index related to its brilliance? Followed by maybe an example, like how lavender Spinel is much more brilliant than a Rose-de-France Amethyst, even though they can be the same color.

    "Fire"of the gemstone, and what it actually is and how it can be measured (dispersion) and compared between stones. How some stones have very high natural dispersion (such as Demantoid) wheras some do not, and how color saturation will mask dispersion.

    Luster of the gemstone. This is one that I personally struggle with, as I am often told that stones with lesser RI's etc still perform very well because of their luster. What is luster? Is it a natural component of the makeup of the type of stone? Or does each stone have a specific "amount" of luster, case by case? Can luster be improved by things like cutting? Is it measurable like RI or dispersion?

    I think these are some examples of things a beginner would also want to understand, as it would help explain other reasons why it may be a better choice to go with that lavender Spinel over that Rose-de-France.


    Also, I would love someone who specializes in the jewelry side of gemstones (which I do not have a clue about!) write up some basic info about what color stones work with what metals and so on. For example, I learned on here that it is generally accepted that "warm" colored stones look better in yellow/rose gold, wheras "cold" colored stones look better in white or whiter metals. Why do some metals enhance some stones, and why do some take away? I understand much of this may be subjective, but there are some of you jewelry gurus that have reputations as experts and many would follow what you suggest. Maybe some basic thoughts could be written down as "basic suggestions" and so on.

    I'll defer to the rest of you to fill in the blanks in this post, to expand and give better definitions and examples, if anyone wants to take the time and effort to do it. I think LD has a great idea here in this post, I'd love to see it expanded upon somehow. Thanks LD et all.
     
  14. minousbijoux
    Super_Ideal_Rock

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    by minousbijoux » Apr 17, 2012
    This is a great idea and would be helpful if added

    However, from what I've observed on this forum, the following is just too subjective to be included as "facts" like the above. As a result, it does not belong in this thread.

     
  15. T L
    Super_Ideal_Rock

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    by T L » Apr 17, 2012
    Great info LD, thanks so much for this.
     
  16. Justin_Cutter
    Brilliant_Rock

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    by Justin_Cutter » Apr 25, 2012
    Bless you LD! Excellent work.

    ~Justin
     
  17. chrono
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    by chrono » Apr 26, 2012
    I don't want to get too technical but will attempt to discuss the definition of brilliance and lustre.

    Brilliance refers to the light that is reflected from the interior of a gem, meaning that the light reflected back to the eye is coloured, not white. In a well cut gem, most or all of the light that enters the stone will be reflected by the pavilion facets and returned to the eye through the crown of the stone.

    Good brilliance = the gemstone will be bursting with color from all angles.
    Poor brilliance = the gemstone will have areas of reduced colour.

    Extinction is the opposite of good brilliance. When the pavilion facets are cut with overly steep angles, the light reflected is reduced in intensity and appears dark aka extinction. When the pavilion facets are too shallow, light passes right through the stone and is not reflected back through the crown at all aka windowing (hence again, little brilliance or a dead center).

    Luster refers to the light reflected from the surface of a gem. All gems have luster (of varying categories) but only transparent stones have brilliance. Luster is broken down into the following:
    1. Metallic
    2. Submetallic
    3. Vitreous or glass-like
    4. Adamantine
    5. Resinous
    6. Silky
    7. Pearly
    8. Greasy
    9. Pitchy
    10. Waxy
    11. Dull

    ETA
    I hope you aren't expecting me to fill in examples for each category, do you? If so, you'll have to wait for another day as I'm tired tonight.
    :mrgreen:
     
  18. chrono
    Super_Ideal_Rock

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    by chrono » Apr 26, 2012
    I made an attempt to explain the relationship between refractive index and brilliance in a gemstone, then gave up. Instead, I managed to find an excellent article that explains it much more clearly than I could ever try. It might get a bit technical and mathematical for some in certain areas but I will cut and paste a few pertinent parts:
    http://www.geo.utexas.edu/courses/347k/redesign/PDF_Handouts/Refraction_reflection_critical_angle_handout_updated_09.pdf

    Refractive index focuses on how light bends when entering a gem. Brilliance in gemstones reflects primarily how light exits the gem. Light leaving a gemstone either; 1) escapes and is refracted away from the normal or; 2) is completely reflected back into the stone. The most brilliant gemstones are those whose pavilion facets (bottom of the stone) act like mirrors, reflecting light back up through the table and crown (top of stone) to the eye. Gemstones whose pavilion facets behave as windows, passing light out the bottom of the stone, look dull and less brilliant. What determines whether light inside a gemstone will be internally reflected or pass through a facet? Two things; the angle at which it strikes the facet and the R.I. of the gemstone.
     
  19. LD
    Ideal_Rock

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    by LD » Apr 26, 2012

    Unfortunately this is one area where you can't say "X" with any degree of certainty! I'm going to give you an example ......

    I, personally, only like rose gold with pink stones (preferably pink diamonds, morganite, kunzite etc). For me, rose gold can enhance the "pinkness" of the gemstone and so you get a more enhanced overall pink appearance.

    TL uses rose gold with virtually everything! :D She is happy to pair rose gold with a blue or green stone for example. For me, this makes me shudder - for TL it makes her smile!

    So who's right? We both are because we put together combinations that appeal to us!

    Generally speaking if you use white gold with a pale stone it will enhance the coldness and the end result may be a very cool icey looking piece of jewellery. If you team a warm vibrant gemstone with white gold it can provide a stunning contrast and because there is more of a contrast it doesn't detract from the warmness of the stone.

    Yellow gold typically suits warmer coloured gemstones and can enhance the richness. However, if you use yellow gold with paler stones the yellow can take over/reflect into the stone and may not look good.

    My advice is to get three pieces of metal (coins are good to use). White. Yellow. Rose. When you buy a gemstone, put it next to all three and take a photo of each one. Walk away and then review all the photos a few days later. One will probably appeal to you more than the others - that's the one to go with.

    Exceptions to any of the above are gemstones that shift or change in colour. Finding a metal that suits both colourways can be extremely problematic.

    Don't forget that skintone of the wearer plays a big part in all this. If you're buying for yourself, put the metal with the stone on your hand to take the photos. If your skintone looks realistic in the photo then you will be able to get a really good feel for whether it will suit you or not.

    There really are NO rules. It's all about personal preference.
     
  20. yennyfire
    Ideal_Rock

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    by yennyfire » May 2, 2012
    LD, I'm really late to this post, but this is EXACTLY what a newbie needs when they want to venture into the CS world. Thank you for taking the time to write this! Bravo!!! :appl:
     
  21. erinl
    Brilliant_Rock

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    by erinl » May 18, 2012
    Can we include information on how to go about buying gemstones from wholesale sources?

    Thanks,
    Erin
     
  22. Arkteia
    Ideal_Rock

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    by Arkteia » May 19, 2012
    Thank you for this post, very helpful, and so well-written, I just enjoyed reading it!
     
  23. Lovinggems
    Ideal_Rock

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    by Lovinggems » May 20, 2012
    Thanks LD! Great post!
     
  24. onedrop
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    by onedrop » May 22, 2012
    LD: thank you for taking the time to write up all that valuable information! I am (was) clueless about colored stones, even though I've wanted one for years, but now after reading your write-up I feel so much better about making a good choice in the future!!
     
  25. minigirl
    Rough_Rock

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    by minigirl » Jun 5, 2012
    thanks fro your sharing. quite useful. :lol:
     
  26. chrono
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    by chrono » Jun 7, 2012
    This is not possible unless you are in the trade.
     
  27. chrono
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    by chrono » Jun 21, 2012
    The following came about from the following thread by Roger Dery with regards to what types of stones are best suited for rings.
    https://www.pricescope.com/forum/post3220969.html#p3220969

    Mohs 9 - Ruby and Sapphire: generally considered the most durable of the colored gems. If untreated in any way, will hold up very well in most all situations. Even those subjected to 'high-heat-only' still do very well. Example: my wife's 2ct oval Sapphire engagement ring was worn daily for 15 years before needing a very minor tune-up. Exception: Ruby that has been filled with substances such as glass have a much lower resistance to damage such as abrasion from wear. Ruby, under high-heat-only with flux present, will also handle wear well.

    Mohs 8-1/2 - Chrysoberyl including Alexandrite: in my experience Chrysoberyl holds up very well against wear. It does not exhibit severe brittleness seen in other gems - and would be a great stone for regular wear as a ring stone.

    Mohs 8 - Spinel: is generally considered a gem that wears well. It is resistant to damage and not just damage from abrasion.

    Mohs 8 - Topaz: can be worn in rings, but some caution should be exhibited. This is especially true with Topaz colored blue because it has been irradiated [and then subsequently heated]. This process has weakened the stone in some way that it does not hold up as well as Precious Topaz - which may, or may not have been treated at all.

    Mohs 7-1/2-8 - the Beryl family including Aquamarine, Heliodore (golden Beryl), Morganite, Goshenite wear fairly well and unless totally exposed from the metal, can be worn in rings though may not be suitable for 'everyday wear'. The heating of any of the Beryl's is done at a low temperature and it is not a factor regarding their durability. Beryl's do have an element of brittleness though not as severe as some other gems.

    Mohs 7-1/2-8 - Emerald (of the Beryl family) is not well suited for everyday wear. A totally clean Emerald will hold up as well as an Aquamarine. But, finding an Emerald with that level of clarity is extremely rare. Roughly 99% of all Emeralds have been treated with a filler of some type to (usually) improve their clarity. The filler is likely to not hold up well over time. *Emerald's that have been treated should not be placed into an Ultrasonic cleaner, nor placed under a steam cleaner as this may affect the clarity enhancement substance. **Caveat: Emerald's treated with a specialized process known as "Excell" in the trade are known to have a higher level of durability over those treated with other methods.

    Mohs 7-1/2 - Andalusite has reasonable wearability though it does have a slight brittleness. Facet junctions are likely to show wear after only a few years regular wear. Distinct cleavage is present in Andalusite though I have yet to see the affects of it.

    Mohs 7-1/2 - Iolite in my experience holds up fairly well for hardness 7-1/2. It does, however, have distinct cleavage and a sharp blow in one or more specific directions may cause it to separate into more than one piece. Though, when I have tried to do this in the rough, I have not been successful.

    Mohs 7-7-1/2 - The Garnet group is generally thought of as reasonably durable. Facet junctions will show wear within the first few years of being worn. And, the facet junctions may not chip as much as 'crumble' for lack of a better way to describe this. Of the Garnets, the Andradite/Demantoid type is the least durable, and we have found the Pyrope/Almandine/Spessartite group seem to wear slightly better.

    Mohs 7-7-1/2 - The Tourmaline group is suitable for rings, though not for everyday wear especially if the top of the stone is exposed. Tourmaline can be brittle, does not hold up well where temperature changes are radical. They are known to 'chippy' as can be seen along facet junctions that are exposed.

    Mohs 6-1/2 to 7-1/2 - Zircon is often thought of as brittle. Zircons heated to high temperatures (over 1,000*C) to convert them to blue are definitely more brittle and show the effects of wear easily. Blue Zircon worn high on a mounting will need refurbishing regularly. Unheated Zircons and those subjected to much lower temperatures (of various colors) are less prone to show wear - and appear less brittle. There is no known dilemma with faceting or polishing Zircon for the experienced lapidary. There is, however, a known direction to its hardness which could create difficulty for some.

    Mohs 7 - The Quartz family is well known due to being available and popular. Its wear pattern is predictable. Facet junctions (even when faceting) can be 'chippy'. Chipping along the crown facets is common, and abrasions from wear are as well.

    *as a general rule, at least from me, I don't suggest wearing hardness less than 7 on a regular basis as the wear will become evident well before you expect it. I do suggest moving this type of gemstone into mountings offering great protection or off the fingers or wrist.

    Mohs 6-1/2 to 7 - Kunzite is not a durable gemstone. It is brittle, does not resist scratching well, does not repair easily, and has perfect cleavage in two directions. In addition to all that, it has the unfortunate problem of being light sensitive - reducing its depth of color with prolonged exposure to direct sunlight. I have repaired my fair share of Kunzite's and I don't relish the fact that they show up waiting for my handy work. But since they don't wear well over time, they will all eventually need reconditioning.

    Mohs 6-1/2 to 7 - Peridot does not share the fate of Kunzite, though its wear pattern is predictable. Abrasions are readily seen on exposed gems that are frequently worn - and fortunately, a refurbishing is not usually problematic.

    Mohs 6-1/2 to 7 - Tanzanite is very popular and goldsmiths have taken to mounting them in lavish and risky ways. Exposed surfaces will show wear in a relatively short time and the perfect cleavage can be a problem. Tanzanite is also heat sensitive - even though it is well known to have been heated to acquire the beautiful blue to purple hues. It is the shock of rapid temperature change that may cause damage. This is not a common situation with consumers as this is more likely to take placec in the creation or repair to a mounting.

    Mohs lower than 6-1/2 - Apatite, Opal, Orthoclase/Sunstone, Scapolite, Sphene and Sphalerite and other low hardness gems all need special care to be worn in rings. It is generally accepted that these gems are best suited for pendants, pins, brooches or earrings.
     
  28. erinl
    Brilliant_Rock

    Messages:
    737
    Joined:
    Jan 22, 2011
    by erinl » Jun 22, 2012
    Chrono:

    I know that I cannot directly buy a stone if I am not a member of the trade. However, how does one buy a stone from a vendor such as pala? What I mean is, where and how does one find the middleperson to buy the stone? Must you be willing to commit to the setting with a jeweler before purchasing the stone?
     
  29. chrono
    Super_Ideal_Rock

    Messages:
    35,897
    Joined:
    Apr 22, 2004
    by chrono » Jun 23, 2012
    Erin,

    I understand your question better now that you have provided specific questions. For Pala, you can request that your local jeweller or online vendor of your choice contact Pala for pricing. Pala has a certain minimum markup for their inventory. Your jeweller or vendor will tack on their own markup on top of that, so choose your middle person wisely. You are under no obligation to commit to any setting with the jeweller before purchasing the stone (due to the markup they have already added).
     
  30. soberguy
    Brilliant_Rock

    Messages:
    637
    Joined:
    Mar 25, 2009
    by soberguy » Aug 21, 2012
    Can someone discuss toughness? As in jadeite?
     

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