Tools to identify diamonds

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.



Edited 2 time(s). Last edit at 11/24/2011 03:59PM by el cascaillou.

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...

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.

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

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).

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

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

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

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.!

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

Probably. What are you trying to prove?

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:)



Edited 2 time(s). Last edit at 09/09/2012 06:44PM by John Oostenryk.

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.

[www.mindat.org]

regards,
stephanie

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

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.