Tom Gelb - Posts





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Re: What is a bruise?

A perfect description, well done.

by Tom Gelb

September 14th, 2012, 8:00 am

Forum: RockyTalky

Topic: What is a bruise?

Replies: 10

Views: 570
Re: What is a bruise?

Hi Kenny, A bruise is a group of small feathers surrounding a single point. They are also called percussion marks (this sometimes made it easier for people to understand). They are certainly damage, being caused by a blow. Whether it happened in the ground or afterwards is very hard to tell, but usu...

by Tom Gelb

September 12th, 2012, 7:46 am

Forum: RockyTalky

Topic: What is a bruise?

Replies: 10

Views: 570
Re: Diamond has tiny piece of orange on the outside- fixable

Hi Yssie, Yes, you would think so, but this seems to not always work. I guess the surface opening is too fine? It is strange that something could get in once and not again, but we may be talking about geological time frames here, versus a pressure or overnight acid boil. Sorry to not have a definiti...

by Tom Gelb

December 3rd, 2011, 2:07 pm

Forum: RockyTalky

Topic: Diamond has tiny piece of orange on the outside- fixable?

Replies: 7

Views: 524
Re: What color diamond doesn't have a yellow undertone?

Hello Yssie, I believe I can shed a little more light here. I worked in fancy colors at the GIA for a number of years. Please note the responses in red below. If you have anymore questions please let me know. All the best, Tom No, I'm definitely not talking about fluor - only the body colour of the ...

by Tom Gelb

December 2nd, 2011, 10:32 am

Forum: RockyTalky

Topic: What color diamond doesn't have a yellow undertone?

Replies: 28

Views: 991
Re: Diamond has tiny piece of orange on the outside- fixable

Hello, It is very difficult to say what this may be. It could even be a piece of dirt. But I thought it valuable to mention that on occasion fractures (what are called feathers in the diamond grading community) can have an orange tint within them. I believe that this is caused by iron oxide (rust) t...

by Tom Gelb

December 2nd, 2011, 10:12 am

Forum: RockyTalky

Topic: Diamond has tiny piece of orange on the outside- fixable?

Replies: 7

Views: 524
Re: Harry Winston Cushion Question

Hello,

I would expect that they have both, but it is likely that there are more modern cushions in their stock as time progresses. Although they can likely procure anything you'd like.

Good luck

by Tom Gelb

November 4th, 2011, 3:04 pm

Forum: RockyTalky

Topic: Harry Winston Cushion Question

Replies: 4

Views: 415
Re: Oppenheimer family to sell 40% stake in DeBeers.

Hi Neil,

I saw this also, but was unsure as to the significance and/or ramifications. What are your thoughts?

Thanks,

Tom

by Tom Gelb

November 4th, 2011, 3:01 pm

Forum: RockyTalky

Topic: Oppenheimer family to sell 40% stake in DeBeers.

Replies: 4

Views: 271
Re: Violet diamonds

Sorry Kenny, not for sale, just under a carat.....and of course, it looks much nicer in person... David, if a FDV just under a carat were for sale (not that heart, a hypothetical one) what would be the price range . . . oh . . . give or take a few hundred thou? Is pure violet more rare than pure re...

by Tom Gelb

October 28th, 2011, 12:20 pm

Forum: Colored Stones

Topic: Violet diamonds

Replies: 44

Views: 1659
Re: Who wants a red diamond?

I hear you. I know that it's the most vauable colour. In person I suspect it's pretty dark though. I got a tiny reddish purple one (I assume it's irradiated), mostly because I wanted to see what they are like in person, and it's just too dark. The picture was great though. Too bad that in person it...

by Tom Gelb

October 28th, 2011, 11:42 am

Forum: Colored Stones

Topic: Who wants a red diamond?

Replies: 63

Views: 3264
Re: GIA cert: Clarity Characteristics

It has now been three years since I left the GIA but I believe that the plotting rules are probably approximately the same. When I was grading all VS and lower inclusions had to be plotted regardless of clarity. So my expectation is that the crystal, feather, and cloud are all VS1. The reason for th...

by Tom Gelb

August 7th, 2011, 9:57 am

Forum: RockyTalky

Topic: GIA cert: Clarity Characteristics

Replies: 9

Views: 1486
Re: GIA grading

Tom, Thanks. Glad to hear that we're talking about an error on the part of a grader on a particulr stone or a misstatement by a PR person and not a systemic problem at GIA. I have a question for you. If GIA rejects a stone for being glass filled, is there some sort of report or letter issued indica...

by Tom Gelb

July 20th, 2011, 12:37 pm

Forum: RockyTalky

Topic: GIA grading

Replies: 25

Views: 525
Re: GIA grading

I left the GIA about three years ago, but when I was working there in the colored diamonds department there was a comment stating "Laser drilling (drill holes) are present". If a colored diamond origin of color grader sees laser drill holes they are required to put this comment in the repo...

by Tom Gelb

July 18th, 2011, 5:13 am

Forum: RockyTalky

Topic: GIA grading

Replies: 25

Views: 525
Re: Diamond Phosphorescence

Hello, I have seen this phenomenon a few times, almost exclusively with blue diamonds. But I think your analysis is correct. The same type of excitement causes fluorescence and phosphorescence, so I expect that when the phos is visible but the fluor is not that it is a function of the excitation wav...

by Tom Gelb

July 17th, 2011, 9:50 am

Forum: RockyTalky

Topic: Diamond Phosphorescence

Replies: 5

Views: 253
Re: GIA (or other lab) reports for small colored diamonds

Quality Assurance Service With an increase in treated and synthetic diamonds in the marketplace, GIA now offers testing for loose and mounted diamonds in the smaller size ranges to help you quickly make determinations about items being offered to you. Available for D-Z and Fancy color diamonds 0.20...

by Tom Gelb

June 26th, 2011, 1:11 pm

Forum: RockyTalky

Topic: GIA (or other lab) reports for small colored diamonds

Replies: 6

Views: 261
Re: Clarity grading question?

What I think they could add to this thread is what you already know, and that is by studying lots and lots of diamonds (and that yeah its can be pretty hard) you will develop the feel and confidence for accurate and consistent clarity grading. Hello Everyone, Just to lend a graders perspective here...

by Tom Gelb

May 28th, 2011, 8:03 am

Forum: RockyTalky

Topic: Clarity grading question?

Replies: 20

Views: 1277
Re: Should I care aboutClouds and Feathers in VS2 Stone?

. Also, GIA will list a feather first, the grade setting inclusion, even if it is the same order as an internal inclusion. For example, in a stone has a cloud and feather at the VS2 level, the feather will be named first. If it is named after the cloud in a VS2 stone, then it will be a less signifi...

by Tom Gelb

May 27th, 2011, 11:23 am

Forum: RockyTalky

Topic: Should I care aboutClouds and Feathers in VS2 Stone?

Replies: 18

Views: 12119
Re: Another Fancy Yellow Diamond with Blue Fluorescence Ques

Tom, I forgot to state the reason I'm asking about this ... UV in GIA's FCD color-grading light may add thousands of dollars or much more to the value of FCDs. Here's why: Blue is one of the most expensive diamond colors. A blue FCD that is a hue grade or two more-saturated is worth MUCH more than ...

by Tom Gelb

April 11th, 2011, 8:26 am

Forum: Colored Stones

Topic: Another Fancy Yellow Diamond with Blue Fluorescence Question

Replies: 10

Views: 2518
Re: Another Fancy Yellow Diamond with Blue Fluorescence Ques

Hello, It is pretty common for a yellow diamond to display blue fluorescence. The Summer 2008 Gems and Gemology article about yellow diamonds reports that of the almost 25,000 diamond in their study about 25% showed fluorescence, and 92% of these were blue. Thus it is not uncommon at all. I am not a...

by Tom Gelb

April 9th, 2011, 8:14 am

Forum: Colored Stones

Topic: Another Fancy Yellow Diamond with Blue Fluorescence Question

Replies: 10

Views: 2518
Re: what does it take for a diamond to crack?

Hello All, When I worked for the GIA they had a service called a damage report. It was usually from an insurance company seeking to find out whether a diamond had been damaged and whether that occurred before or after the diamond was last polished. My expectation is that the insurance will cover thi...

by Tom Gelb

April 8th, 2011, 5:45 am

Forum: RockyTalky

Topic: what does it take for a diamond to crack?

Replies: 31

Views: 2309
Re: enough is enough..at what point will the consumers say..

Hello All, Dancing fire, as to your specific example a 20-25% increase over a 7 year period averages out to less than 3% compounded annually, so you could have put that money in a CD and seen about the same increase, also about the same as inflation, so this makes sense in real dollars. I agree that...

by Tom Gelb

April 6th, 2011, 6:28 am

Forum: RockyTalky

Topic: enough is enough..at what point will the consumers say...

Replies: 32

Views: 1932
Re: Fake GIA Cert/inscription detected / Tracing the source

I would suggest that you contact the GIA, as they are very concerned about this issue and would likely try to do something.

Good luck

by Tom Gelb

April 4th, 2011, 6:30 am

Forum: RockyTalky

Topic: Fake GIA Cert/inscription detected / Tracing the source

Replies: 6

Views: 2103
Re: AGS vs GIA color grades

What also happens is that both GIA and AGS have a similar procedure of accepting stones, giving a first grading-result, leaving the option to ask for a re-check (disagree) and then issue a final grade. I have never met a retailer (sending in stones to GIA) who knew about the GIA-procedure, and thus...

by Tom Gelb

April 1st, 2011, 8:32 am

Forum: RockyTalky

Topic: AGS vs GIA color grades

Replies: 40

Views: 2768
Re: can you do 2 treatments to a stone without ruining it

Hello Starz, One can certainly do two treatments to a stone if they are done in the right order, and they are the right treatments. As noted above subjecting any clarity enhanced diamond to heat (sometimes even in setting) can cause damage to the filler making the fractures obvious again, so the cla...

by Tom Gelb

March 18th, 2011, 5:57 am

Forum: RockyTalky

Topic: can you do 2 treatments to a stone without ruining it

Replies: 17

Views: 408
Re: New here - help with yellow diamonds?

Thanks RD, Tom, Kenny, and everyone else for addressing my question - this has turned into an interesting discussion! And OP hope you didn't mind the discussion. Kenny - I've also seen charts describing impurities as they correspond to colour - though they are always prefaced with disclaimers of in...

by Tom Gelb

March 11th, 2011, 11:04 am

Forum: RockyTalky

Topic: New here - help with yellow diamonds?

Replies: 25

Views: 1104
Re: an extra facets affect the clarity grade?

An extra facet will not affect the clarity grade in any way. One could have an internally flawless diamond with an extra facet. I hope this helps.

by Tom Gelb

March 9th, 2011, 9:36 am

Forum: RockyTalky

Topic: an extra facets affect the clarity grade?

Replies: 6

Views: 558
Re: New here - help with yellow diamonds?

Thanks RD, Tom, Kenny, and everyone else for addressing my question - this has turned into an interesting discussion! And OP hope you didn't mind the discussion. Kenny - I've also seen charts describing impurities as they correspond to colour - though they are always prefaced with disclaimers of in...

by Tom Gelb

March 5th, 2011, 2:58 pm

Forum: RockyTalky

Topic: New here - help with yellow diamonds?

Replies: 25

Views: 1104
Re: Comparative Colour

I am planning to purchase a stone I saw recently. It's 1.74ct, F, VS2, Excellent cut. However, this is from the Gemscan precert (I am in Toronto). I've read a number of things about Gemscan and there seem to be camps on both sides of the issue. I don't mean to re-raise the reliability of Gemscam ag...

by Tom Gelb

March 4th, 2011, 10:30 am

Forum: RockyTalky

Topic: Comparative Colour

Replies: 2

Views: 224
Re: Is polish grade normally reduced after setting?

Hello,

Given the extreme hardness of diamond (and by hardness I mean resistance to scratching) the polish should not be affected by the metal of the setting not matter how rough it is. Remember that the only way to polish a diamond is with another diamond because it is so hard.

I hope this helps.

by Tom Gelb

March 4th, 2011, 10:17 am

Forum: RockyTalky

Topic: Is polish grade normally reduced after setting?

Replies: 1

Views: 133
Re: New here - help with yellow diamonds?

If I might butt into your thread w/ a quick coloured diamond q for RD or others shattrstar - RD - random question, but do you find that some inclusions help saturate colour (or tend to de-saturate)? I'm thinking about something like (sufficiently severe) wisps that impedes light return, which could...

by Tom Gelb

March 4th, 2011, 10:11 am

Forum: RockyTalky

Topic: New here - help with yellow diamonds?

Replies: 25

Views: 1104
Re: New here - help with yellow diamonds?

The source of the color in colored diamonds is . . . Yellow: nitrogen contamination. Blue: Boron contamination. Pink/Brown: deformation of the Crystal lattice structure when the diamond was formed. Green: proximity to radioactivity. FCDs do not get their color from inclusions . Of course a really l...

by Tom Gelb

March 4th, 2011, 10:03 am

Forum: RockyTalky

Topic: New here - help with yellow diamonds?

Replies: 25

Views: 1104