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Techniques for CollectorsTools to identify diamonds

20th Jan 2010 21:37 UTCDiane Kniskern

There are many brands and models of "diamond detectors" available online. Does anyone know what kind would be the most reliable to test rough stones found at the Crator of Diaminds in Arkansas? I've looked at the thermal conductivity models and I like the ones which claim to identify colored gemstones, as well as diamonds, but I don't know how much I need to spend to get an accurate one (or if they work at all). I've also looked at refractive index testers and thought the two might be a good combination. Does anyone have experience with any of these? Thanks.

20th Jan 2010 21:43 UTCAlfredo Petrov Manager

Diane, if you familiarize yourself with the appearance of natural diamond crystals, you won't need the testers - Rough diamonds are visually distinctive. Start with the photos here on Mindat. The staff at Crater of Diamonds should be able to teach you more.

Furthermore, the refractometers and thermal conductivity testers that jewellers use are designed for use with polished surfaces; they won't work so well with the rougher surfaces of natural uncut crystals.

21st Jan 2010 00:56 UTCDean Allum Expert

Diane,

A UV lamp, or the thermal conductivity detectors already attached to your hands are less expensive than the gem meters.

-Dean A.

21st Jan 2010 03:09 UTCMatt Neuzil Expert

I am not familiar with the cost of RI fluids but I think some scrap corundum would at least work for a scratch test... and should rule out anything else.

21st Jan 2010 09:09 UTCAlessio Piccioni

I agree Matt Neuzil, sometimes i use the same sistem for identify cut diamonds from cut zircon. Remember Diane, the diamonds are the only stone resistant to carborundum scratch.

24th Jan 2010 17:02 UTCDiane Kniskern

Thanks for the replies, but I still need an answer to my question about which testing devices are most reliable.

Having been at the Crater of Diamonds many times and having seen numerous diamonds found there over the years, I am quite familiar with the appearance of natural diamonds. If I were lucky enough to find something like the 'Easter Sunrise' or the 'Okie Dokie,' I would agree a tester is unnecessary. However, diamond finds of that magnitude are extremely rare at the Crater.

Though I do appreciate your suggestions: most of the finds are far too small to test for coolness with your fingers. Not all diamonds are florescent. Due to the extreme brittleness of genuine diamonds, doing a scratch test could easily shatter them, so it is not recommended. In addition, though some rough diamonds (like Billy Moore's 'Frosty') do have rough surfaces, many have a natural highly polished surface conducive to thermal testing. I also have colored crystals from North Carolina I would like to test.

The Crater's Diamond Discovery Center has wonderful interactive exhibits, demonstrations, and videos, and the staff there does a great job educating the public. Some staff members try to take the time to identify each speck of mineral brought to them, but when it gets busy in the summer, it is nearly impossible for the staff to closely examine all the tiny shining crystals clutched in the sweaty hands of hopeful visitors waiting in line, especially at closing time. It's easy to understand why, after identifying a hundred handfuls of calcite and quartz, a tired staff member might just give a quick glance and say, "Calcite and quartz."

I have several small stones I would like to test which visually appear to be diamonds. They are probably too small to be cut or have much value, but I wouldn't sell them anyway. I would just like to know for sure. I have photos, but don't know to submit them. Alfredo, if you can identify diamonds by sight, please tell me how to get photos to you. Thanks.

24th Jan 2010 22:12 UTCAlfredo Petrov Manager

Diane, your Mindat access has already been activated, so you can upload any photos on your computer into Mindat. Just go to the Mindat Manual at:

http://www.mindat.org/index.php/Main_Page

...and then click the line about uploading photos, for instructions.

When you are using Mindat, you should see a button in the top left hand corner of the scren - "My Home Page" - Click on that and your own personal space on Mindat will be accessed (Yours is still empty). You can upload photos, articles, blogs, there.

24th Jan 2010 23:36 UTCDiane Kniskern

OK, I put three pictures on my page (I think). Hopefully I did it correctly and didn't break any rules.

25th Jan 2010 14:07 UTCDavid Von Bargen Manager

If you just want to upload photos to the messageboard, just click the "Attach a file..." link in the gray area above the new message entry box.

25th Jan 2010 15:41 UTCDiane Kniskern

Thanks, David.

The tiny crystals in the attached photos (shown in a 2 & 3/4 inch peanut butter lid) are all about 1/16 inch in diameter. I collected them two weeks ago near Murfreesboro, Arkansas. Do they look like diamonds (though too small to be of value) or just quartz?

PS: What is the best material on which to photograph tiny minerals?

25th Jan 2010 18:07 UTCLachrisha Smith

Diane, I bought a tester and it has all the stuff. after a few yrs. of mineral collecting I realized my eyes were better for identification on most my minerals. although it is great for cut stones,..I dont recommend it for rough.its important to visually rely on your eyes.as the rough stones will be easily identifiable through scratch test and crystal form, I think. accsesory minerals can also help in identifying a mineral species.The diamonds at crater park could be seeded as well.so I have heard. either way ,..study diamond rough here on mindat, and remember nothing sticks to a diamond and they do feel greasy.I did look at your pictures and it looks like quartz to me. hope this helps. and the tester most used is a presidium duotester : (presidium instruments usa 255-4 big run road lexington ky 40503) is where i got mine, but you can get them anywhere. best wishes, Lachrisha

25th Jan 2010 18:34 UTCDiane Kniskern

Lachrisha, thanks for answering my question!

I've often wondered if any of the larger diamonds found at the park might be seeded (the ones in the photos sent out in the email newsletter that cause me to drive back to the Crater from Virginia), but I've seen quite a few small ones actually being found, so I know they are there. I found the crystals in my photos outside of the plowed search area. Guess I'll go 'turn the jar over' and see if they fall out of the peanut butter! Diane

25th Jan 2010 21:14 UTCDavid Von Bargen Manager

The park itself isn't doing any salting. Some people have been known to bring in some diamonds and say they were found there.

26th Jan 2010 01:12 UTCJames Christopher

Lachrisha Smith Wrote:

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

> The

> diamonds at crater park could be seeded as well.so

> I have heard. either way ,..study diamond rough

> here on mindat, and remember nothing sticks to a

> diamond and they do feel greasy

Don't diamonds stick to grease?

26th Jan 2010 03:01 UTCSteve Hardinger 🌟 Expert

The specimens in the pictures look to me like quartz. They do not appear to have the somewhat greasy luster of natural diamonds. But then again, photos can be deceiving.

26th Jan 2010 19:48 UTCDiane Kniskern

Speaking of which, whatever happened with Eric Blake? I haven't heard anything about it since last year.

21st Apr 2010 09:52 UTCJamey Swisher

First off, any and all testers for colored gemstones are not going to be accurate plain and simple as they can not tell the difference between a synthetic and a natural stone and often times stones also overlap so it can not distinguish between certain materials. These devices are really only worthwhile, accurate, and useful to those with an education in Gemology and when used in conjunction with other tools. That said, the Presidium Reflectivity tester is one of the better units out there, especially with the extended chart converting reflectivity index to refractive index. But again, it is only useful to tell the difference between certain materials, like diamond and cz or the like, and such without training and without being used in conjunction with other tools.

A nice hydrostatic specific gravity setup would be far better and more useful for ID'ing gemstones. Especially combined with a refractometer or reflectivity meter.

27th Oct 2011 17:21 UTCFDray

Yes pic 0058 has 3 diamonds, middle right, lower left, and lower center. 0054 has three, maybe four, top three for sure, and maybe lower left. without a loupe would be hard to tell on that one. 0049 has one the others are to blurred to see. A simple test is with a small red lazer, put the stone on bright white printer paper in the dark. With the lazer in front of you, so no light is bounced back to your eyes if it is a diamond, put the lazer right on the stone with the lens touching. Put a beam through the stone, the crystal structure of a diamond will bounce the beam and split it inside to make it glow red with bright points of light, quartz will pass the beam, much like glass.

27th Oct 2011 17:41 UTCFDray

Diamonds will only stick to grease in a sluce, or in water. Diamonds are hydrophobic, none wetable, so will stick to grease in water. All other stones have a wet surface so they have no contact with the grease.

27th Oct 2011 18:18 UTCJohn Betts

A UV lamp is NOT a good tool for identifying diamonds. Diamonds fluoresce when activated by X-rays. But of the thousands of diamonds I've sold only a handful fluoresced under Ultra-Bright SW UV.

Any diamonds found at Crater of Diamonds should be certified by the Park Service where they will issue a certificate about the size of a business card verifying that it is a diamond and the weight.

Lastly, almost any jeweler will have a diamond tester that measures thermal conductivity and can distinguish between diamond and simulants. There is no need to buy a tester, just befriend your local jeweler.

23rd Nov 2011 05:15 UTCcascaillou

concerning rough diamond, note that there can be:

-diamond crystals glued on kimberlite matrix or into conglomerate (or even man-made conglomerate)

-diamond substitutes (such as topaz or phenacite) being cut in the shape of diamond crystals (with false trigons being carved to make these more convincing)

-if the stone has no identifiable shape, it could be any natural or artificial substitute

-rough diamonds being treated to improve or modify their color (irradiation, hpht annealing, dyeing)

-hpht synthetic diamond crystals (but their geometry is actually a bit different from natural diamond crystals). CVD synthetic diamonds crystals are not a concern as they do not look anything like natural crystals.

the first of identification tools should be your eyes and a 10x jeweller loupe.

20th Aug 2012 17:08 UTCChandra Reddy

Hi All,

I have a rough diamond with irregular shape and it's quite difficult for me to understand whether it is a diamond or natural stone. It is exhibiting full white light when i spotted under a tiny torch. Please advice me in order to find out...

20th Aug 2012 19:45 UTCOwen Lewis

Size? Transparency?

Can you take a a well-focused and sharp picture or two?

It you can just take it to a friendly local jeweller who should be willing to test it with thermal conductivity tester for you.

Or, if you want to DIY (and in addition to testing the thermal conductivity), if the crystal has good clarity, no serious inclusions and you have access to a properly calibrated analytical balance, you can find if specific gravity. Properly done and temperature corrected, you should expect the value to be within the range 3.510 - 3.525. Check whether or not the crystal is isotropic (cubic system) by rotating it in a polariscope. If you have no polariscope, lay the crystal on a laptop screen opened out flat and use a lens from a pair of polaroid spectacles as the analyser.

Neither of the following can help you identify a rough Diamond crystal:

- A total internal reflection refractometer (Diamond is out of range for this instrument type and almost certainly you do not have a surface that is both large enough and flat enough to test.

- Any of the diamond testing/gem testing reflectometers. Almost certainly you do not have a surface that is both large enough and flat enough to test reliably.

As Cascaillou suggests, with some experience of handling rough Diamonds, you can get quite reliable results with just your eyes, a x10 loupe, and a light source balanced for daylight.

25th Aug 2012 22:57 UTCmitch delgado

attached are 4 photos

found these 10 years ago wyoming colorado N.W. border

took to pawn shop used their diamond tester got a faint green light

these were handeled for some time before that

weighed on gold sscale 5.3 and 4.2 grams

i recently took to a jewler, he looked at them with 10 x loupe

he looked them over pretty good

explained the cuts the light refractions shooting outward

he gave me a mineral store in fountain co. to take and have them urther test

what do u think

26th Aug 2012 01:05 UTCOwen Lewis

Sorry, but I think those photos are of no use. There is nothing to see there that is clear or which might relate to Diamond. At the weights you give (about 26 and 21 carats respectively, if they are Diamond rough, you have a sizeable fortune on your hands. But, as said, there is no reason at all to think that is the case from what you show.

Try photgraphing them again. Do not place a strong light behind them. Photograph outside in cloudy daylight if possible and if not on a table with a strong white light placed close to the side of the camera or try a flash. Don't get too close; pull back a bit until the stones are sharply focused.

Many pieces of of diamond rough show a complete or partial crystal form but some look more like a water-worn pebble - or even just a broken crystal fragment. Turn the stones under the light, Diamond will show a high light return from any cleavage or fracture, however small. Here are some examples of what Diamond rough can look like - as you see, it's quite varied. These stones are all less that one hundredth of the weight of yours BTW.

Look also at the the 287 photos of Diamonds in the Mindat photo gallery. But be aware that these are mostly specimens of above average quality. You need to look at many to even begin to appreciate the range of differences that can occur and the extremely high lustre that is the common factor to them all when viewed appropriately 'face-to-face).

29th Aug 2012 11:08 UTCmitch delgado

Hello Owen, Thanks for responding.

If u are comfortable, would u plz E-mail me - mitchdelg@ymail.com

I have taken some pics , would like u to review

29th Aug 2012 11:38 UTCmitch delgado

Hello, Forum;

Here are 3 new pics , I took pics with the following:

1. 5 dollar magnifer/ stand from Harbor Freight . Had a 3/4 Dia. addition internal lens. (has 2 small led lights underneath)

2. 2 dollar double magnifer. Placed this on the 3/4 lens.

3. A 12 year old digital camera.

4 Used a software to resize

Would like to hear bavk

Thanks Mitch

29th Aug 2012 15:08 UTCWayne Corwin

Sorry Mitch

Those blurry photos won't help at all.

You need to do a specific gravity test, hardness test, and

try doing a macro photo.. front lit by sunlight.

Wayne

29th Aug 2012 17:12 UTCSpencer Ivan Mather

I agree with John here, and there are no refractormeters on sale that can measure the refractive indces of diamonds, it is too high. After looking at your photo's I can see only a few possible diamonds, the rest are most likely quartz.!

9th Sep 2012 04:10 UTCmitch delgado

If one were to put 2 tables spoons of Crisco shortning at the bottom of glass canning jar'

Put jar in water filled pan- heat water in pan - until Crisco liqufies

Fill 3/4 with water

Suspend quartz specimen in center of jar w/ fishing line- dangling from lid at the level of water ( quartz 1/2 in solution 1/2 above)

Would the grease particles stick to the quartz as the grease cooled

9th Sep 2012 14:04 UTCWayne Corwin

:-S

9th Sep 2012 17:49 UTCDonald Peck

Probably. What are you trying to prove?

9th Sep 2012 19:41 UTCJohn Oostenryk

Uh, Mitch, you are making a heck of a mess. I hope you didn't do that. That process you referred to has nothing in common to the 'Kimberly' sorting method with petroleum grease. And don't try to do that either! You''l just end with a greasy/oily rock... If you have criscoed it, hot water, dishsoap, and toothbrush-clean it up, noone wants to mess with a slimy rock.

However, Solution!

TWO options- very simple.

As you have found, jewelers work with cut stones, not rough, and their methods are utilized with pcs usually already set in jewelry. You have 2 clean rough pcs, I can make that out from the blurred photos. Specific gravity weight calculation is the best test you can do on a specimen like that.

Call your local high school, ask to have the earth science teacher to ring you back. Ask if he can do a specific gravity test on a small solid material for you. If he can't go to option 2.

He will have the scale, but you need a little tinkering to support the object in the water, for the second weight to make the calculation.

Spec grav = (wt of object dry) divided by ((wt of object suspended in water*) MINUS (wt of object dry)).

*That does not mean object is just sitting on bottom in water! It must be suspended, and the scale tared to account for that apparatus.

The weights should be at least two decimal places in accuracy to calculate. For example X.XX has 2 decimal places.

It should be between 3.516–3.525. Then do a hardness test. Maybe he has some pieces to try with. A garnet at 7, or better yet corundum at 9, crystal scrap will not scratch a diamond at 10.

That should be EASY with their help!

OR...

You are somewhere there in the Front Range, call the Colorado School of Mines (1500 Illinois Street, Golden, CO 80401) PH(303) 273-3000.

That is the general contact #. Explain to the secretary you might have a couple of rough diamonds, can she direct you to a professor or student to make an appt and have them weigh your pieces for specific gravity for you. Then contact who she says, or give them your #, and go to the appt. It should take 5 min to weigh on their apparatus. While there, have them show you a set of hardness picks too. #9 wont scratch a diamond... That way you will know what they tell you is truth- no more uncertainty or messing around.

Very easy and very clear, problem solved!

Please do post back here and let us know what the outcome is.

JohnO:)

9th Sep 2012 19:52 UTCStephanie Martin

As previously posted in the other thread for Mitch, in case it was missed, here once again is the link to the thread on how to do a specific gravity test. It is much simpler than fuddling with that grease test you were attempting. Scroll to page 2 for Reiner's easy method. If you don't have an appropriate type scale, then try the school or university as was suggested. This really should not be that difficult to sort this ID out if you follow our advice.

http://www.mindat.org/forum.php?read,11,250282,page=1

regards,

stephanie :-)

23rd May 2013 18:49 UTCD-M-D

Hi Guys

I would like to know about the carat for this piece of rough Dia with measurement 3 x 2 cms.

And also approximately its market value !

Regards,

D-M-D

23rd May 2013 20:37 UTCDavid Von Bargen Manager

What type of gemstone is it? You really can not give a value for facet rough without looking at the stone in person and with magnification.

23rd May 2013 22:24 UTCOwen Lewis

More particularly, why do you say it is diamond (at 3x2 cm...)? How do you know?

23rd May 2013 22:44 UTCBob Harman

Yet another silly post asking for all kinds of info based on this horrible quality photo of a small lump of opaque off white something. Even the given measurements of "3 x 2 cms" are rather silly in reference to info on diamonds. D-M-D, show whatever you have there to an ethical jeweler or certified gemologist and let him/her evaluate it in person! CHEERS...........BOB

24th May 2013 04:45 UTCLeor Goldberg

If you are worried about diamond vs quartz, a simple scrap corundum scratch test would more than suffice. Unless you plan on keeping the crystals that is. For the record though, they look a bit too gemmy to be found there. Not that it doesn't happen, I just find it highly unlikely that you found four of them; I would have to agree with Tim on this one.

25th May 2013 08:40 UTCD-M-D

Hi again guys...

Thank you for your responses on my post, with much appreciation.

The stone is a rough diamond.. Rest assured, all tests on diamond have been successful.

The 3 x 2 CM is the measurement of this gemstone with a simple ruler on Height by Width;

Also, I do not want to handle this gemstone to a gemologist.. for just imagine this scenario: I give that to the gemo to analyze it and he puts it into his pocket or drawer. And tell me politely, go home my friend : ) Then.. what do I do !!

"Never trust a stranger "

This is the reason why I posted it here for a humble, sincere opinion.

I just require an approximate evaluation.

For the photo.. it has been taken with my laptop webcam... Wherefore money buys many and this is why my photo is of low quality.

Thank you for your response.

Cheers

D-M-D

25th May 2013 12:50 UTCD-M-D

Some more pics.. Thank you

25th May 2013 13:44 UTCD-M-D

Check it out Diggums ^^ Thanks

25th May 2013 13:52 UTCWayne Corwin

Man, those are still way to blury, but still looks like quartz,

16th Jul 2013 11:55 UTCGoddan5

Can anyone help me and say whether the diamonds in the picture are genuine they range from 6 to 10 carats.thanks Ps if other pictures are required will post

16th Jul 2013 14:43 UTCBob Harman

My guess is that no one will venture any opinion based only on your pix. Where are they from? How did you come by them? Do you implicitly trust their history prior to coming into your possession? All these questions must be asked and answered. After that they may all be genuine or fake and any combination of the six may be real or fake. So no one will render any meaningful opinion based only on your pix. Personally, with diamonds or look-a-likes, I would take them to an ethical or reliable jeweler and have them examined in person......never by photos alone. CHEERS...........BOB

16th Jul 2013 16:49 UTCDonald Peck

Bob's comments are right on the money. Your stones "look like" diamonds, but you need a gemologist to verify them. A guess from a photo is just that, a guess.

16th Jul 2013 17:15 UTCOwen Lewis

Well, a fool rushes in where angels have the sense to keep the mud off their Jesus boots....

Your photos are not good but we've seen a lot worse here. The crystals are transparent-ish, fairly colourless, seem relatively unincluded and many of then are clearly of the cubic system. So far, so good. But I see no strong lustre and the lustre on most uncut and generally well crystalised diamonds is usually easy to spot.

So what next? If these are diamonds you are sitting on fortune that is not small. I would *not* take them to a jeweller or pawn broker. Many have never seen an uncut diamond, let alone ones of this size. They need to be seen by a party that is absolutely trustworthy - and that means an expert and reputable lab and paying them properly for their services. Check their charge rate before deciding to contract with them. So, before putting your money where your mouth is, you need to be more sure that they *probably* are diamonds - and then handle accordingly.

Prepare for this as follows:

- If you do not already have one, buy a little scale that is provably accurate (test weights) to two places of decimals in ct wt. These complete with a little density determination kit start at about USD 90.00. You can PM me for details. You then need to use this rig to determine the SG of each of your stones. If diamonds, the SG of each, calculated three timess and the result averaged, will be 3.52 +/- 0.01 if they have only minor inclusions.. If they have this SG, are cubic, and colourless, you should then treat any such as though they were diamonds and be prepared to pay for an expert examination and certification.

Rather than a jeweller, you could try to find a friendly pharmacist who, for a bottle of good whisky or whatever, will let you stand and watch as he calculates the SG of your stones for you on his analytical grade balance. Don't let them out of your sight other than to a trusted third party.

Don't on any account, try to 'scratch test' them - unless you like gambling with several thousand dollars.

Hope this helps. Assuming you are in the US, I'd recommend any of the following (google for addresses):

- West Coast. G.I.A, Carlsberg CA

- Mid-West. Stone Labs, Greater St Louis area..

- East Coat. AIG. NY NY.

Elsewhere, check for a recommendation from the gemmological institute of your country.

You actually (if diamonds) face a two-stage expense on expert advice:

1. Are these real diamonds?

2. What are they worth? As you may find out in due course, there is more than one possible answer to this second question, depending on where you are and the route than you are prepared to pay to travel before collecting you money..

Good luck :-)

16th Jul 2013 18:37 UTCBob Harman

OWEN , When I said a "jeweler" I meant it in the widest generic sense of the word. Don't tell me about this aspect as much of my family was in the NYC diamond business and they were, not only very ethical, but they could evaluate all manner of diamonds. Cut and uncut, real and various look-a-likes, colored and all shades of colorless, clarity etc etc. They were jewelers and stone faceters and gemologists, sometimes all together.

The poster, GODDAN 5, first has to know all about his stones and their history to start with. Then have an ethical gemologist or similar individual evaluate them individually in person as to not only their authenticity, but their quality, clarity, inclusions, and exact weight etc etc.

One of the worst ideas is to have a novice fiddle with them and try to test them. This then becomes the blind leading the blind and many wrong inferences may result. Finally, the whole identification process becomes so muddled that no one believes what anyone else says. CHEERS........BOB

16th Jul 2013 19:51 UTCOwen Lewis

Sorry Bob, no slight to your family intended and I hope none taken. A NYC diamond trader is not one's average nowhereville jeweller.

With that family background, maybe you'd care to outline to the OP the various options open to him to maximise his return, if he is sitting > 50 ct of gem quality rough diamonds in the size-range 6-10 ct each? Starting with an answer to the question, where did you get these and what is your proof of title to them?

28th Jul 2013 12:07 UTCcascaillou

Hard to tell from blurry pictures, but there might be simulants (topaz, phenakite, quartz, etc...) cut in the shape of natural diamond crystals.

SG test is a good idea, keeping in mind that if SG is around 3.52 that might still be topaz. Other than that, observation of surface and internal features is the way to go.

28th Jul 2013 12:38 UTCOwen Lewis

Topaz ain't cubic and ain't got no diamond's lustre ;-)

28th Jul 2013 13:39 UTCcascaillou

topaz has a slightly greasy lustre which make it kind of suitable to imitate rough diamond crystals which also often show greasy lustre. Of course, the topaz crystals do not look like diamond crystals, but they can be cut to mimic the shape of a rough diamond crystal, and triangular striations can be carved to make the whole thing more convincing, see here:

http://www.gemlab.net/gemlab/fileadmin/user_upload/Publications/Gemlab-PhenakiteTopaz-RoughDiaScam-04-2008.pdf

Whatever, I'm very suspicious of the appearance of Goddan's stones

28th Jul 2013 14:08 UTCOwen Lewis

We are missing each other. I am not talking about the form presented but the crystal *system* (if any). Topaz is not of the cubic system.That's a 30 sec check to find out. Now... *IF* the pieces are cubic *and* have a 3.52 SG, what will you say?

These pieces seem to have a good clarity. When did you last see a diamond of gem grade with less than an adamantine lustre? Lustre is an inherent quality. ''Greasy' does not come with high reflectance and dispersion.

28th Jul 2013 14:23 UTCcascaillou

this is SLIGHTLY greasy to me: http://www.johnbetts-fineminerals.com/jhbnyc/gifs/49880.htm

Cut diamonds never look greasy though.

Anyway I do agree that you might indeed check for isotropy (not only with polariscope though), still observation under magnification might be enough to separate from topaz.

7th Sep 2013 13:38 UTCkevo

I found dis rock today it looks like a rough diamond I tried to scratch it with

tha point of a sharp knife didn't scratch

Scratched another rock it left a scar

7th Sep 2013 14:25 UTCRob Woodside 🌟 Manager

Quartz

7th Sep 2013 14:30 UTCOwen Lewis

Update on GODDAN 5's stones.

The following is lifted from the web site of GCI labs in Israel:

'Last week GCI Gemological Centers received from the Goverment Diamond Control, a parcel of 346.07 carat of crystals, imported as natural rough diamonds from Tanzania. The importer was sure that he got genuine diamonds. The crystals in the parcel had a shape similar to natural rough diamonds, and some of them showed noticeable surface lines, "positive triangles", frosted surfaces, internal inclusions and fractures. Specific Gravity was close to that of natural diamond . After testing and inspection of the goods at GCI laboratory, all the parcel was identified as topaz crystals - not even one single diamond !!! , The surface lines were engraved intentionally on the crystals'.

Within the limits of GODDAN 5's poor photos, there are strong similarities between the stones he showed and the pieces reported on by GCI Labs See the trigonal surface markings in particular; though strongly supporting a visual identification as diamond, these are not present on the majority of gem diamond rough crystals. You can see the excellent GCI imagery of these fake diamonds here http://gci-gemlabs.livejournal.com/5771.html.

The relevance to this Mindat topic area lies in the certainty that even experienced traders in diamond rough can be expensively defrauded by relying on visual ID and 'heft' alone. 10 seconds rotation between crossed polars would be sufficient to raise a large warning flag over such stones and trigger a full examination.

A deal of skilled work would have been necessary to cut and finish these fakes. It is quite unlikely that this parcel is the first to have found its way into the diamond supply chain or that it will be the last.

El Cascaillou's point that the lustre of some diamond and some topaz can be confused has been well proved.

7th Sep 2013 20:32 UTCBob Harman

OWEN , Thanks for your continuing followup. The outcome just further proves my point. ANY Mindat poster with pictures and a question like GODDAN5's should be referred to an ethical and competent gemologist for complete in person and hands on evaluation of the stones. NO GUESSES or suggestions of trying to do "tests" on the stones. Clever fakes are just that.....CLEVER FAKES! CHEERS.......BOB

8th Sep 2013 14:39 UTCOwen Lewis

We'll have to agree to disagree, Bob. :-)

The essential point I draw out here is that the fakes had been passed by one or more experienced rough diamond buyers who, clearly could have accepted them on no more than experience + visual + heft. They never could have passed the standard gemmological tests had such ever been applied prior to acceptance. When, down the line, an Israeli govt agency sent the parcel for testing, the testing was emphatic that all were artfully fashioned from topaz. Testing rules OK?

6th Jan 2014 03:45 UTCshajaan

yesterday I have found a crystal stone on a clif of a mountain, it was covered by the thick layer of dried leaves of pine.. it was white and clear. its seems like an ice cube. it was very hard.. when I scretched it on a morror it has a scar.. and when I put my mobile flash light into it, it was very bright.. due to attachment of some hard rocks at the backside of the stone I cannot read the newspaper through it. when I breadth it has no fog... but I want to confirmed whether it is a daimond or just n ordinary stone.. pliz reply n help me.. my contect no is +917308359404.. email at; monichingkhei@gmail.com

8th Jan 2014 14:42 UTCRock Currier Expert

Shajaan,

Impossible to say without a picture. Even with a picture it may not be possible to say without further tests. Many minerals will scratch glass. Try scratching a ruby or corundum crystal with it.

24th May 2014 00:53 UTCkenny s

Hi i hope you can help this may sound silly but i think i may have found a diamond , i dont no who or where to take it can you help

24th May 2014 02:23 UTCBob Harman

KENNY S , It is actually rather simple to get started. If you live near any university or college with a geology department or state geological survey they will help you get started without taking the example physically from you. Just ask at the office who you should show it to.

If you live in any medium or larger city, take your example to any reputable jeweler. They are almost always quite ethical and will preliminarily evaluate your find or refer you to a competent gemologist.. For initial preliminary evaluation they will just need to see your find and probably not need to physically take it from you for evaluation. If it is seriously promising they will tell you of the steps you need to take to confirm the stone's identification. If you live away from civilization, make your way to a larger city with hi end jewelers/gemologists.

The vast, vast number of found diamonds are too small to permit individuals to do self testing like specific gravity or scratching glass, etc etc. Have the stone looked at in person by a knowledgable individual!

But recognize that the chances of your stone really being a diamond are relatively small so prepare for disappointment.

Hope this helps GOOD LUCK AND CHEERS…..BOB

23rd Aug 2014 16:31 UTCarun

Please can you tell me the 3m emery sheet scratch rough diamond stones.

23rd Aug 2014 17:36 UTCDoug Daniels

No, they won't. Emery is made of magnetite and corundum, both of which are "softer" than diamond.

4th Oct 2014 06:46 UTCfor jebel

A. Hi Dear Professor

According to the photos it is a diamond or not

4th Oct 2014 17:28 UTCDoug Daniels

No. And, the chart given is kind of useless; I doubt many of us here can read Arabic (?), so we don't know what the chart is showing us.

26th Oct 2014 14:24 UTCVakerie

Hello My.name is Valerie and I'm have a hard time Idet those rough about I throw them out I was told that you guys here the best Thank you!

26th Oct 2014 19:15 UTCDoug Daniels

The photos are quite blurry, but the stones are most likely river-tumbled quartz/jasper/chalcedony/chert.

19th Jul 2015 20:41 UTCWhitehat

Hi I would love some feedback on this picture to see if I am on the right track.

Please advise as I do not have access at the moment to correct tools to asses

20th Jul 2015 03:12 UTCOwen Melfyn Lewis

You need tools as follows:

1. A balance and hydrostatic rig capable of determination of SG, error free, for the size of stones you have. to 2 decimal places. Diamond, along with a small number of other mineral species, if transparent and virtually included (as your crystals seem to be) should have an SG of 3.52 with a tolerance of no more than +/- 0.01.

2. A polariscope, to determine whether the crystals are isotropic or anisotropic. To look at the crystals, they should 'isotropic'. i.e. cubic. However, within the last couple of years topaz rough, skillfully carved to present as cubic octahedral crystals has entered the diamond rough supply chain more than once. Topaz is the only colourless crystal with the same SG (and 'heft' in the hand) as diamond.

If your stones pass those two tests, it is highly likely that your crystals are diamond and you should have them professionally checked using other instruments to determine their colour grading and clarity, with plotting of such inclusions they may contain. Along with that information an appraisal of value becomes possible.

If they are diamond and at the sizes you indicate, you could be looking at (at least) a five figure sum.

20th Jul 2015 19:47 UTCWhitehat

Thanks for the input I did manage to take a closer look with my basic magnifying glass.

When shining a light or in the sun it is spectrum less no rainbow colors.

Also when reading a newspaper I cannot see directly through it.

Passed a basic scratch test with sandpaper and Quartz

20th Jul 2015 22:45 UTCOwen Melfyn Lewis

Doesn't help much, I'm afraid. It's not possible to say much more working just from your images, beyond saying that they *look* like worn colourless/near colourless cubic octrahedral crystals. Outside of deliberate fraud, that leaves seveal possibilities and you will need to get at least one (I suggest the biggest one) properly tested by someone who has the equipment to do that and is trustworthy.

Where/from whom did they come from? How did you come to get them?

21st Jul 2015 03:13 UTCWhitehat

Currently in central Africa close to one of the mines

21st Jul 2015 10:33 UTCOwen Melfyn Lewis

Whoopsiedoo! :-)

Time to get real. You *know*what you need to do. Just get on with it...

21st Jul 2015 15:39 UTCReiner Mielke Expert

"Passed a basic scratch test with sandpaper " what kind of sandpaper? If it is carborundum sandpaper and you can't make a mark on it then I would say you have diamond.

19th Nov 2015 02:39 UTCRobert Hobdy

Here's a list of tools I use which are easy to acquire to test if its a diamond. A good electronic scale capable of measuring to a 100th of a carat. You can create your own string noose to hang in water, but I use the stuff you clean teeth with and a small plastic drinking cup. That way I measure weight and displaced weight for specific gravity. Get a smooth corrondum crystal (ruby or saphire) large enough to scratch with your diamond. It will leave a definate scratch on the corrondum crystal that cant be wiped off. Get your self a bottle of WHINK from Walmart. You will find it in the drain cleaner area. It contains a very weak solution of Hydrofluoric acid. Be careful how you handle it and do not use glass, use plastic only, as it will eat anything that has silica in it. Diamonds are pure carbon and wont be affected by it. It will etch the surface of virtually every other crystal out there because they all have silica as part of their chemical composition. Of course, get your self a good microscope of 10x to 60x which are available for under $100.00. Your crystals do look like the real thing...they have the correct crystal shape.

19th Nov 2015 17:14 UTCOwen Melfyn Lewis

Hi Robert and welcome,

Here are some thought on your list of analytical tools for diamonds

Robert Hobdy Wrote:

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

> Here's a list of tools I use which are easy to

> acquire to test if its a diamond. A good

> electronic scale capable of measuring to a 100th

> of a carat.

Yes, that's the *minimum* accuracy required but working with a scale accurate to +/- 0.1mg is much better. When working with specimens of about half a carat, a +/- 0.01 ct scale approaches borderline for determining an accurate SG.

> You can create your own string noose

> to hang in water, but I use the stuff you clean

> teeth with and a small plastic drinking cup. That

> way I measure weight and displaced weight for

> specific gravity.

Only good for specimens larger than a couple of carats. Below that the inaccuracies inherent in that method get greater repidly as the specimens get smaller. And have you ever tried tying a noose around, say a 0.05 ct diamond? ;-) I don't know the size of your diamonds but at least half of mine are smaller than 0.1 ct.

The uselessness of this method of SG determination for application to really small stones is shown absolutely by the very inaccurate results obtained. If you search the 'Identification' topic area, you will find long chats about the inaccuracy of this method when applied to small stones. You can also find details of how to make yourself an SG determination kit that will do the job accurately down to maybe 0.1 ct.

> Get a smooth corrondum crystal

> (ruby or saphire) large enough to scratch with

> your diamond. It will leave a definate scratch on

> the corrondum crystal that cant be wiped off.

Good test. Best is to trawl e-Bay for half-boules of flame-fusion synthetic corundum. These cost about USD 17.50 each and one only will last for years and over a hundred tests without any need for repolishing. But have you ever tried holding a 0.1 ct diamond and scratching anything with it? ;-)

> Get

> your self a bottle of WHINK from Walmart. You

> will find it in the drain cleaner area. It

> contains a very weak solution of Hydrofluoric

> acid. Be careful how you handle it and do not use

> glass, use plastic only, as it will eat anything

> that has silica in it. Diamonds are pure carbon

> and wont be affected by it. It will etch the

> surface of virtually every other crystal out there

> because they all have silica as part of their

> chemical composition.

Hmmmm... Too many other materials contain no Si for this to be useful. Most rough diamonds have a degree of 'etching' to their surface appearance.

Try using a polariscope instead. At least it will eliminate clean crystals that are doubly refractive for you.

Actually for a first sort, the only tools you need are equipment to get a really accurate SG from diamonds of the size you work with (SG 3.52 +/- 0.01 or else its not a pure diamond) and also a polariscope differentiate diamond from topaz that can have the same SG as diamond (nothing else does).

Of course a jeweller will use a 'diamond tester' that checks the hear conductivity but IMO, these are not the best tools - but they are quick and easy to use. Not so good for small rough stones though, that most jeweller's never get to deal with.

> Of course, get your self a

> good microscope of 10x to 60x which are available

> for under $100.00.

'Good microscope' and 'under 100 bucks' is a contradiction in terms. Also, one needs the microscope to examine what is going on inside the crystal. One can't normally do that well with a rough diamond other by using some *very* fancy (=expensive) techniques. For most of us with good but ordinary gemological microscopes, their usefulness is largely confined to the examination of polished stones - where they do become an essential tool. For rough diamonds (and incidentally the quality grading of cut and polished diamonds, stay with a x10 triplex loupe.

>Your crystals do look like the

> real thing...they have the correct crystal shape.

And that you cannot trust to. Read back in this thread.

19th Nov 2015 18:19 UTCReiner Mielke Expert

How about two sheets of fine carborundum sandpaper. Put the diamond between them and rub for a while. If the diamond shows signs of rounding then it is not diamond. Why not use heavy liquids for S.G. What about the grease test?

12th Mar 2016 15:53 UTCMamady Konate

Sorry Mamady,

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