Transparency in diamonds, and other C's

[Garry H (Cut Nut)]

This is an interesting article in a review of a diamond author Renée Newman:
https://www.diamonds.net/news/NewsItem.aspx?tc_dailyemail=1&ArticleID=63680
"Transparency matters
Newman distinguishes between clarity — a stone’s lack of inclusions and other blemishes — and the first “T,” transparency, which is how well it lets light pass. While a diamond with high clarity will have few or no inclusions, a stone is transparent if a viewer can see objects through it distinctly. Many laboratories don’t take into account subtle differences in transparency, Newman writes. “I’ve seen hazy and slightly cloudy diamonds with VS clarity grades,” she notes in the book. "

I will mention again my dismay at GIA's (and probably other labs) that use the term 'Clouds' to describe diamonds that are translucent. I see many of these diamonds from VS2 down that are 10x loupe clean but dull.
A decade ago I contacted Tom Moses, the boss of GIA grading business about an SI1 stone that was what many of you would call a fancy white diamond. Here is his response:

Dear Garry,
A senior staff member finalized this stone. GIA uses transparency master stones for this category of grade determinations. Our records indicate that there was deliberation between SI1 and SI2 with a final decision made as SI1.
Best regards,
Tom
17387607 is the GIA number.
CLARITY CHARACTERISTICS
Clarity Characteristics
Cloud

 

[AV_]

I riddle GIA's guide to its plots, as to be saying that the 'clouds' that are plotted (a contour of red dots) are contained within that area - as opposed to "Some [other] clarity characteristics are not plotted on the GIA reports if they are widespread or faint, or they are not needed to support the clarity grade or identify the diamond."

From: WWW

It does not help that both are 'clouds' - possibly for dearth of English words...

Does this much hold?

 

[bmfang]

She has those 5 C’s and 2 T’s outlined very clearly in the digital edition of her Gem & Jewelry Pocket Guide that I have on my phone.

 

[Karl_K]

Bottom line diamonds are graded at 10x and things smaller than 10x viewable can have an effect on the transparency of a diamond.
Multiple sources have stated that more rough is being sold these days that will cut into diamonds will issues than ever before.
Partly because the mines are producing more sleepy rough and partly because the miners found out that cutters will pay for them.

 

[Double E]

Interesting topic. So many may worry, how risky are stones with additional clouds not shown? As this indicates certain amount of clouds at least viewable under 10x magnification, although it’s not further affecting clarity grade, is it going to impact the transparency to some extend?

Can consumer simply trust the vendor for the transparency issue (luckily many PS recommended vendors are willing to assure guest their diamonds don’t have transparency issue)? And can we interpret “diamond isn’t hazy / milky / oily” from vendors as no transparency issue?

 

[Garry H (Cut Nut)]

Interesting topic. So many may worry, how risky are stones with additional clouds not shown? As this indicates certain amount of clouds at least viewable under 10x magnification, although it’s not further affecting clarity grade, is it going to impact the transparency to some extend?

Can consumer simply trust the vendor for the transparency issue (luckily many PS recommended vendors are willing to assure guest their diamonds don’t have transparency issue)? And can we interpret “diamond isn’t hazy / milky / oily” from vendors as no transparency issue?

This is an area that I know of at least 3 organisations working on - unfortunately GIa is not one that I know of - but hey - lets hope they are!
For many years I have been telling and helping on this board with the warning - don't try to get the cleanest SI or VS diamond. The cleaner the stone in photos etc - for it's given grade - the more likely it will have transparency issues.
But say you are looking at a 1ct SI1 stone and there is a crystal that looks like it is bigger than VS2 and there is at least one other type of inclusion mentioned before a cloud (in that vertical order on the report) or a cloud not drawn but mentioned - then the cloud is not a problem.
And good vendors 1. would not have the diamond inhouse. and 2. they should call it in or have a dealer they have a personal and serious biz relationship with eyeball the stone.