Best way to tell if a colored diamond is coated?

[jnl123]

I have some pink colored diamonds that I inherited from my grandfather who was a jeweler. I have never looked at a colored diamond with a loupe before and have no idea what I should or shouldn't be looking for. When I looked at a few of the pink diamonds with a loupe with an LED light attached to it I see portions that show almost yellow to green and not pink. Almost like there is a marbled effect or that in some it's like a "slice" (as in shape only not a specific facet)on the pavilion is yellow/green. I assume this means it was coated as I would assume the diamond color should be consistent throughout. Before I waste money sending one off to GIA does this sound like a coating or another treatment? I have read a carbide scribe can scratch off the coating to tell if it's coated. Is this true?

 

[diagem]

Some pink Diamonds possess a banding/zoning (play of color zones) when viewing with a loupe, yellow green colors I never noticed in pink Diamond material. Sometimes clarity enhancement produces a spectral color glare but it hard to tell with no images.
Depending on the size of a Diamond, GIA grading costs are not so terrible and are sometimes well worth the investment on rare color suspicions.
Scratching a Diamond with anything but a Diamond should reveal if it's coated but I wouldn't advice someone not familiar with handling Diamonds to try. My first question would be, are you certain these are Diamonds?

 

[jnl123]

They're definitely diamonds. I have a diamond tester which indicated they were diamonds and hung around my grandfathers store long enough to know something, but I am not a jeweler. My grandfather had his own storefront in NYC on 47th street for almost 50 years and he labeled them diamonds. I would be shocked if he were wrong. But I am definitely suspicious of it's treatment. I will try and post a picture here a little later.

 

[jnl123]

Here is one that is listed as reddish-pink. I have it sitting on the LED light of my loupe. You really can't see the color differentiation without the strong light. The yellow/green stays constant irregardless of it's position and does not "play with the light". Has to be coated right?

 

[diagem]

Sorry, never saw this phenomena..., also the yellow green coloration are not symmetric to its facet design (facet coating) which might indicate internal as opposed to external. I wouldn't be able to advice you any further without a physical inspection..., good luck and please come back an inform us on your findings...,

 

[Texas Leaguer]

I don't know how big these stones are that you are talking about, but the color looks quite intense with at least decent clarity. Considering the potential value, I highly suggest you send one of them to GIA so that you know what you are dealing with. I agree that the green looks very suspicious.

 

[jnl123]

Yes, I'm fully aware what the price could be if it were to be graded as a natural color. I was hoping someone could give me an idea of what to look for on a coated diamond or what the odd coloration is. I assumed it must be coated to have such a strange coloration when held to intense light. As far as I know diamonds can't have 2 completely different colors. It almost "marbles" the diamond in my opinion.

 

[Texas Leaguer]

You indicate you have multiple stones. Do they all show this effect?

 

[jnl123]

No. Not all do. The most intense pinks and more reddish-pink ones have this odd coloration. The lightest ones look normal to me though a loupe.

 

[Texas Leaguer]

Most likely not natural. Could possibly be coated or something else. Here's a GIA article on coating. You can see two distinct colors but nothing like what you show in the photo.
https://www.gia.edu/gems-gemology/lab-notes-calcium-fluoride-coating-on-fancy-pink-diamonds
For me, it would not be a waste of money to send to the lab to get some certainty.

 

[diagem]

Yes, I'm fully aware what the price could be if it were to be graded as a natural color. I was hoping someone could give me an idea of what to look for on a coated diamond or what the odd coloration is. I assumed it must be coated to have such a strange coloration when held to intense light. As far as I know diamonds can't have 2 completely different colors. It almost "marbles" the diamond in my opinion.

Diamonds can definitely possess numerous colors within its material but those are usually caught in the planning stages and divided accordingly. I strongly agree with Bryan and also think submitting to GIA would be the best first step in this specific occasion.

 

[Karl_K]

My answer is I don't know.
In my very every limited experience when compared to Byron and Yoram I have seen enough weird things with diamonds that I would not be to quick to discount them being untreated.
I would send some of them off to GIA.
Maybe one that shows the green and one that don't.
That is really the best way.

 

[jnl123]

@Texas Leaguer thank you for linking the GIA article. I have a 60x loupe and with that loupe it doesn't have that blotchy appearance. Where it is reddish-pink it is solid and where it has that yellow/green it is solidly that color. Weird. I guess I'll have to send it in now.

 

[Karl_K]

Please let us know what you find out.
I am super curious.
Thanks

 

[WinkHPD]

I too vote for a trip to GIA, but more importantly I am CURIOUS as heck about what that color zoning might be.

It is possible that both of the zoned ones came from the same mine and have a unique color zoning. It is possible they are coated, it is possible.... ai yi yi there are just so many possibilities, please share the results with us!

 

[ChristineRose]

Does anyone else think of watermelon tourmaline? I know you used a diamond tester but thanks to e-Bay the world is now flooded with horrible diamond testers. I know this is not consistent with what your grandfather said though.

 

[jnl123]

@ChristineRose I definitely thought of watermelon tourmaline but it's too dark of a red/pink color and I have a Presidium tester which I trust. It also looks like a diamond under a loupe, just the coloring is the strangest thing.

In the even that GIA has no clue what happened to it what would they write on the cert.?

 

[kenny]

@ChristineRose I definitely thought of watermelon tourmaline but it's too dark of a red/pink color and I have a Presidium tester which I trust. It also looks like a diamond under a loupe, just the coloring is the strangest thing.

In the even that GIA has no clue what happened to it what would they write on the cert.?

I seriously doubt GIA will be clueless.
They are the authority on FCDs and have seen everything people have tried in order to scam buyers.
Yes, staying on top of new scams is a cat and mouse game, but you said you know the long-time provenance of these stones.

I agree that GIA is where these stones need to go.

Hopefully for you they'll determine the material and the color are BOTH of natural origin and issue FCD grading reports.
If something else is going on they may opt to issue no report and just tell you why.
If that is the case, I have no idea what their fee would be; I'd ask them up front.

If someone was crazy enough to coat real fully natural FCDs I suspect the coating could be removed, perhaps by boiling in (sulfuric? acid) ... a task reserved for pros.

Look up GIA and call them in NY or California.
You do not need to go through a jeweler; they deal directly with the public.

Good luck.

 

[Texas Leaguer]

Examine the facet junctions very carefully under magnification. A diamond will have very sharp facet edges, a non diamond will likely have abrasions. From the picture the bezel facet that is reflecting appears to be abraded, but it is is very hard to tell from the photo.

 

[jnl123]

It's just the picture. It looks like a diamond to me, sharp facets. GIA has it now.

 

[bmfang]

Non member of the trade following this thread and I'm looking forward to hearing what GIA come back to you with. Here's hoping for the best.

 

[kenny]

Non member of the trade following this thread and I'm looking forward to hearing what GIA come back to you with. Here's hoping for the best.

+1 I was just about to post a request for update.
Fingers crossed here for you.

jnl123, you said you had several pink diamonds.
Did you send all or just one to GIA?

 

[jnl123]

I sent 2 to GIA. The red/pink one and an orange/pink one.

 

[jnl123]

My estimated return date was today and is still showing in process at GIA. Is no news good or bad?

 

[MollyMalone]

My estimated return date was today and is still showing in process at GIA. Is no news good or bad?

Don't fret (or start celebrating just yet). The delay doesn't mean anything other than GIA is backed up, unable to get the reports & your stones out the door by the estimated return date.

 

[kenny]

Don't fret (or start celebrating just yet). The delay doesn't mean anything other than GIA is backed up, unable to get the reports & your stones out the door by the estimated return date.

+1

With GIA I wouldn't worry about whether my diamond was safe.
I'm pretty forgiving of deadline slips when something important absolutely must be done correctly.

 

[jnl123]

It looks like a new service was added to one of the stones and not by me. Under CDIOR (which is the service I selected) it now says IM. What is IM?

 

[Mavin]

It looks like a new service was added to one of the stones and not by me. Under CDIOR (which is the service I selected) it now says IM. What is IM?

Gemological Institute of America, Inc. 5355 Armada Drive
Carlsbad, CA 92008 USA
Hours: Mon - Fri: 7:30 a.m. - 5 p.m.

T +1 800 421 7250 ext. 7590
T +17606034500

 

[jnl123]

It's too early to call either NYC or CA locations which is why I posted here. Thanks for the number though!

 

[jnl123]

Apparently IM service means inscription service. I didn't request the service and while I don't have the report back I have to assume the stone is treated because it seems GIA automatically inscribes treated stones.