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Calling Pandora!

Okay, back with numbers - I happened to be on the phone with him when you posted...

Stone 1 - over $20k
Stone 2 - over $10k
Stone 3 - $7k

I like the first and third best. I think the first 2 are very expensive...
 
Wow, THANKS. That was quick! You must have a good relationship with your jeweler.

What are your thoughts on the price of #3?
 
He's a friend who happens to be a jeweller rather than a jeweller who happens to be a friend if that makes sense. I don't usually call my jeweller for a chat on a Friday evening!

No 3 is gorgeous. With this stone you are paying for the great colour, the Burmese origin and the fact it is unheated. It faces up a nice size for its weight and the cut looks good. I've never seen a bad stone from Pala and their photos are pretty true to life. I don't think it's a bad price.
 
Didn't want to hijack the other thread, but since this one is to call Pandora, I will hijack this one for a bit :loopy:

You mentioned you wanted to learn about rough, so I will attempt to convey some hard learned lessons for you.

Learning about rough is really a lot more about common sense, than it is about mineralogy/gemmology. This is really a broad subject, but since you are a Cert GA, I assume you have the basics, and know the difference between hardness, toughness, clarity, color, zoning, stress fractures, healed stress fractures, secondary mineralization, twinning, alpha and beta twins, ghost crystals, parting, physical fractures, cleavage, strain, crystallographic classes, hemimorphs, pseudo-morphs, microcrystalline, cryptocrystalline, and the optical planes.... if you do -then toss all that stuff out. Cause all you really need to know is 3 basic things... Color, Clarity, and Shape.

We have said it before in countless threads, Color is everything. If you don't see it in the rough, it won't be in the finished stone. Since rough gems, with the exception of crystals, rarely exhibit a polished face for you to look into the stone, you will need to examine it with a strong light source behind it, I use a small pen light (pen torch??), that projects a narrow but intense white light beam. Holding it behind the intended rough should give you an indication of the body color of the rough and any zoning of color, if you are able to see through the piece without much trouble, very transparently, then you should look for inclusions, veils, cleavage planes, fractures, etc. The more there are the less likely for a clean stone. There is also something to be aware of in that you are using transmitted light, this will tend to make the material appear less saturated than it really is, so much so, that some stones will not cut well at all. Amethyst, may be too dark to cut well in larger stones, so that nice large rough piece you are about to pay a premium for will actually cut smaller stones better than one large stone you may be salivating for - make sense?

Shape of the rough plays a role in the return you can get, and some natural shapes, crystals, are more likely to cut certain shapes of stones than others. I don't usually approach the rough with the intentions of cutting a certain shape stone, I let the general shape of the rough lead me into a shape. Often the rough will cut more than one stone, I try to get a single stone out of it, but sometimes that's just not the prudent thing to do, in those cases I try to make as few separations as possible, you don't get any return from your rough with saw cuts, even when you use the high speed paper thin kerf blades, so try to get pieces that will cut single stones. If that's the case you might wonder why you would ever buy anything else, well sometimes you have too. I was once offered a gorgeous imperial topaz rough, it was large, but the color was oriented in such a way, that I would have to cut multiple stones out of it, it became a very expensive lesson in economics.

There is a lot more, but tell me if this is what interests you, and any questions, I will try to answer.
 
Thank you so much for this!

The Cert GA doesn't cover the things you mentioned in great detail - but the Diploma does, and having hated crystallography at the beginning I'm now pretty keen on it. I did have to check out 'ghost crystals' - wow, I've not seen one of those, but am now going to hunt them down (Nat. Hist. Mus. first port of call). Also alpha & beta twins - which I did know the gist of but not the name - so thank you for giving me some extra knowledge there!

Anyway, good news to know that I don't need all that...

I'm fairly confident that I wouldn't make too many huge errors on colour, and I can pick out the super-included stuff and the rough where the shape is just not going to yield much in the way of a economically viable stone. Where I feel my big lack of experience and knowledge lies is in knowing the best orientation for different species and applying that to an actual piece of rough.

For example, I know that tourmaline should have the table perpendicular to the c-axis for the pinks and parallel for the greens, but is this just what is taught in the time that can be spent on cutting in a course that covers a-z of gemmology or is it actually true?

Then there is the business of taking cleavage and pleochroism and the like into account.

One example that I really find scary is sapphire rough. I recently looked at a load of very nice bipryramidal crystals that had significant colour-zoning. Looking at finished stones, many have the zoning when looking through the pavillion but the cutters have know exactly where to place the stone in the rough to get the best colour when seen from face-up. Obviously if it's an amazing piece with fab colour all the way through it's a lot easier - but you will also pay $$$ for it in the first place. I'm not in a position to make expensive mistakes and so I need to start with the cheaper stuff that might just yield a winner.

I'm not planning to facet myself - husband has banned me as he says I'm too much of a pedant and it'll take me a week to be happy with one stone - but I will have access to cutters in the future and while I'm sure they know exactly what to do with a given piece of rough it doesn't help me if I have to buy the stuff in the first place! I'm likely to be buying in the field.

My tendancy is to throw myself on the mercy of experts and ask for advice and guidance and no doubt I will be doing that - and spending a fair amount of time watching lapidaries - but would be good to know if there are any books that would be useful in advance. Doesn't matter if they are pretty technical as I have the basics on the crystal structures and on colour/light theory etc . I'm not looking to run before I've learnt to walk but I'd prefer to not fall over too much in the process!

Regarding lights, is a common or garden penlight sufficient or should I really buy one of those bizarre looking torches with the teeny light on the end of the massive tube with the super-huge batteries that they all use in Thailand/Sri Lanka (and that cost a bomb!)
 
orientation is easy -just orient for best color - done. There are a few tricks, and zoned stones can be quirky, particularly sapphire but again orient for best color display and make sure the culet of the stone is in the color zone and that's it. As for a light, you can get all fancy, but the best light I have ever used, and about the only thing I use in the field or even at home is this:

http://www.photonlight.com/products/Photon-Micro%2dLight-II-LED-Keychain-Flashlight.html

Batteries last about 24 hours continuous, that will examine a lot of rough, but I just carry a spare set or two, and it's handy for finding your car at night too :)

pleochroic stones like tanzanite, et al - again just orient the rough for the best color and then deduce if it's a viable piece, I see a lot of tanzanite rough that just doesn't make the grade in the economics, either it has poor color and will cut with good return, or you have to cut it in the shape of a carrot to get good color.

Tourmalines - again orient for best color, you can't always tell where the c axis is, but if you have an extinction then you just found the c axis :P . a lot of tourmaline rough is water worn nodules, actually a lot of rough of all kinds is water worn nodules, so crystal faces are actually a rare sight. Makes no difference though, again you want to orient the stone for best color. carry a vial of clear fingernail polish, and on stones that have a rough exterior that you would like to see the interior put a coat or two of clear polish on it, not as good as having a window polished on the rough, but it takes a lot less time. Of course the dealer has to be willing to let you do this, but they usually don't mind, and if they do I usually stay clear of it.
 
MontageCreations|1306605897|2932562 said:
orientation is easy -just orient for best color - done. There are a few tricks, and zoned stones can be quirky, particularly sapphire but again orient for best color display and make sure the culet of the stone is in the color zone and that's it. As for a light, you can get all fancy, but the best light I have ever used, and about the only thing I use in the field or even at home is this:

http://www.photonlight.com/products/Photon-Micro%2dLight-II-LED-Keychain-Flashlight.html

Batteries last about 24 hours continuous, that will examine a lot of rough, but I just carry a spare set or two, and it's handy for finding your car at night too :)

pleochroic stones like tanzanite, et al - again just orient the rough for the best color and then deduce if it's a viable piece, I see a lot of tanzanite rough that just doesn't make the grade in the economics, either it has poor color and will cut with good return, or you have to cut it in the shape of a carrot to get good color.

Tourmalines - again orient for best color, you can't always tell where the c axis is, but if you have an extinction then you just found the c axis :P . a lot of tourmaline rough is water worn nodules, actually a lot of rough of all kinds is water worn nodules, so crystal faces are actually a rare sight. Makes no difference though, again you want to orient the stone for best color. carry a vial of clear fingernail polish, and on stones that have a rough exterior that you would like to see the interior put a coat or two of clear polish on it, not as good as having a window polished on the rough, but it takes a lot less time. Of course the dealer has to be willing to let you do this, but they usually don't mind, and if they do I usually stay clear of it.
Click to expand...

Those lights look great - and nice and small, can you replace the batteries? I'm currently using a Zelcon Flexi-Light http://www.amazon.com/Zelco-Long-Reach-Flexible-Flashlight/dp/B00006JJKZ which are nice as you can wrap them round your hand - and stick blue-tac/balance tweezers on them to hold stones for spectrums etc (I tend to use transmitted light rather than reflected for spectrums). The beam is moveable from pinpoint to wide and comes with a sparebulb and red-filter (that I have never used).

Small PSA here: My favourite bit of kit is actually my Belomo loupes - love them and have never found another that I like as much. Company is owned by Zeiss and so you get their optics for a bargain price, plus they're hard-wearing, black-cased and bigger field than most.

I have a tiny portable folding polariscope - would it be worth using that with a conoscope to find the c-axis or is it just too much time/hassle in the field? Or is it just going to be obvious where the best colour is and make your judgement call on that?

Is nail-varnish better than oil? What happens if you put it on something like peridot rough? I've seen what bathroom cleaner can do to that!

If you are looking at water-worn pebbles, and are judging orientation based on colour then how do you square that with cleavage planes such as in topaz?

Sorry, lots of questions!
 
Don't be sorry lass, I used to teach college chemistry while I was in graduate school, I love questions :appl:

the photon light is very small, about the size of our quarter and about 5-6 mm thick, it has 2 replaceable batteries (need a small philips head screwdriver). and I like it cause it has great utility and intense beam, you can glue a dot of velcro on it and put the other half of the velcro on the brim of your hat, on your tweezers, etc. It is also very lightweight, so lugging it and 2 changes of batteries up the side of a mountain 3 km and back is not encumbering in the least.

I have never had nail polish effect a stone, and I routinely use it on peridot, any an all common gem rough is not a problem, haven't used it on opal rough or turquoise, but didn't need to on them either. :P

I used to carry, Polariscope, conoscope, refractometer, dichroscope, and a wide field microscope, did that for about 2 years - hardly ever used any of it. What you really need, that stuff won't help you with any way, you need to be wary, there are good honest dealers and there are the disreputable, but even the honest ones will try you for the fool the first meeting, just to see if you are the tourista or a professional. All I have ever really needed, was the light, tweezers, oil/nail polish, pocket knife, and a healthy dose of skepticism.

If you really know the crystallography, crystal habit, mineralogy of your hunt, then you are already armed with 99% of what you need. A good field guide in mineralogy will supply you with the physical specifics, and I used to pack my Dana's system books with me, leaving them at the hotel or camp (they are heavy), to research locality information, crystal habit, cleavage, etc.

Even water worn nodules of topaz will show some tendencies for flattening on one or more sides, that is the indicator of the cleavage plane, but in all honesty, I haven't bought topaz rough in the field for at least 15 years, I don't waste my time with field study of topaz rough, when I can buy it by the kilo for pennies a gram - make sense? same goes for most amethyst, citrine, ametrine, etc. There are regular bulk suppliers of that stuff almost everywhere, especially on the internet. Establish some good contacts with reputable dealers and they will tell you when they have something of interest, has worked for me for years.
 
So basically concentrate on learning what to look for in the less than common or garden stuff or things that can't be bought by the kilo?

Agree on not needing half the kit. The last time I bought some cut stones out in Sri Lanka I had brought the whole caboddle (bar microscope which I have hardly used) and the only tools I took out were tweezer, loupe, pen-torch and a dark-field.

Also definitely agree that you will be tested to see if you know what you are up to. My tutor likes to tell a story about a couple of his students who popped over the border to Burma during a field-trip to Thailand and came back with amazing 'bargain' rubies. They hadn't expected to find synthetics so close to source! He was buying himself in a market and said that the hands came out with stones, he picked one up and looked at it and gave it back saying 'thanks but not interested in glass' - apparently every hand disappeared and he saw only good stones from then on!

Mind you, that kind of thing happens everywhere: I was checking out some pink spinels for a PSer here a couple of weeks ago. I went to see a dealer whose stones I have seen a few times and he has some very nice stuff. He didn't recognise me at first and when I asked to see the pink spinels he pulled out a tray and pointed to one as a nice example. I didn't even pick it up, just said I wanted to see stones without windows please. He laughed, put the whole tray away and went and got one from the safe with stones of a whole different quality - then said, hey don't I know you... :bigsmile: Makes me mad that they do this though - I hate seeing my friends with ugly stones. If people didn't sell ugly it would be so much better.

I guess the best way to learn is going to be making a few, hopefully not too expensive, mistakes, looking and watching. It's potentially even more fun than opening stone-papers!

Are there books with diagrams of the basic traditional cuts and how they fit into pieces of rough - or is it a case of feeling what the stone tells you?
 
ah yes the inevitable vetting of your knowledge. I had a good friend take a trip to Africa, about 30+ years ago, and while on Safari he was made an amazing offer, which he of course fell for. They convinced him, by scratching a piece of glass, that he was buying real diamond rough, he paid $15,000 for 100 ct of diamond rough in beautiful pastel shades. When he came home he poured out his treasures to me, and the alarm bells were already going off before I even looked at them. They had a specific gravity of 2.52, but even before that they were 8 perfect octahedrons, that's as far as I had to go, but he wasn't convinced. I pulled out my pocket knife and scratched a piece of glass in front of him and told him that the bulk of the gem world could scratch glass. He was flabbergasted that someone would fleece him like that....

If you have the option of mentoring with someone, that would be ideal, if not then stick to reputable sources that have a history and presence, even if you pay a little more for his cut it's probably worth it, there are few short cuts worth while. I have seen a few books that have diagrams of cuts, but to tell the truth they are so old I don't remember who wrote them. I may be thinking of Glenn Vargas treatise on "Faceting for the Beginner", or maybe John Sinkankas (he wrote many books) try a library for them.

Also we can try a little quiz. If you saw the following shaped roughs what would be your suggestion for cutting?
1. a grape shaped Ametrine with the color evenly split though the center
2. a date shaped rough of spessartite
3. a carrot shaped rough of tanzanite, with the best color in parallel with the long axis of the rough
4. a crystal section of tourmaline with an open axis, what about if it's a closed axis

see how you do with those, there isn't a right or wrong answer, this is just an exercise to get you to think in 3d
 
MontageCreations|1306627531|2932754 said:
Also we can try a little quiz. If you saw the following shaped roughs what would be your suggestion for cutting?
1. a grape shaped Ametrine with the color evenly split though the center

I think ametrine looks better in stones cut to show the bi-colour effect rather than cut for light performance so I'd try for something like a modified version of a shield or barion or tapered baguette. If the rough is shaped like a grape then it seems a shame to just cut a common or garden EC and waste the depth.

2. a date shaped rough of spessartite

Oval, barion or elongated cushion cut.

3. a carrot shaped rough of tanzanite, with the best color in parallel with the long axis of the rough

Okay... I'm probably going to completely screw this one up, but here goes! (I'm working on the basis of the 'long axis of the rough' being the axis down the longest direction rather than it being the c-axis)

If the material is unheated then you will see red/yellow/green/brown down the c-axis, violet down the a-axis and blue down the b-axis. If heated you drive off the red/yellow/green/brown and it will look blue down the c-axis.

So, if the stone is unheated the long axis of the rough is likely to be the b-axis (given that the best colour is in parallel), so you want to orient the table so that the blue is predominant, so you place the table perpendicular to the long axis and cut a round brilliant. Biggest loss of material but best colour of stone. If the rough is big enough you might get two stones, one much bigger than the other.

If the stone is heated then I would put the table parallel to the long axis and and cut a trilliant. The colour may not be as fine as if the table were perpendicular but given that you have blue down both the b and c-axes you don't have any nasty colour to deal with. The question would be whether to orient the violet a-axis or blue c-axis perpendicular to the table. I prefer violet blue tanzanites to blue blue but the market disagrees.

Well, that's my theory! :bigsmile:

4. a crystal section of tourmaline with an open axis, what about if it's a closed axis

Open axis - depends on the colour! Let's imagine a nice pink, then I would cut as many round brilliants as the rough would allow all with their tables perpendicular to the c-axis.

If it's a green then it would depend on the dichroic colours. If both nice then rbs again, if icky then an emerald cut with table parallel to c-axis. Indicolite - most likely an EC with table parallel to c-axis to minimise any green.

Closed axis - table parallel to the c-axis, elongated emerald cut with ends and pavillion cut at steep angles.

see how you do with those, there isn't a right or wrong answer, this is just an exercise to get you to think in 3d
Click to expand...


Feel free to criticise! Open house to others to do likewise! :bigsmile:

Would be very interested to hear what you and any other cutters reading would do with these examples of rough.
 
MC - please ignore everything I have written about the tanzanite. I think I have had a totally duh moment and I'm going to try and sort my head out over biaxial stones and optic axes and then have another shot...
 
Pandora,

Haven't forgotten our ongoing discussion, just been busy tending to business, will have a discussion on your answers in the next day or two.
 
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