Internal and external graining confusion

[lovedogs]

Hi all,
Im trying to get better at seeing internal/external graining for my never-ending search for an overblue fluor stone. Most stones under 1ct dont include that info on the GIA report, so im stuck trying to see it myself.

This helpful article from WF shows some pics of internal graining:

Understanding Diamond Graining: Insights & Impacts on Clarity

Graining is a common diamond characteristic that is sometimes noted on a laboratory report and may affect its clarity grade. Learn about types and impacts of diamond graining here.

www.whiteflash.com

That said, I still have a few questions:
1. When I see "streaks" on a diamond, that's internal graining, right?
2. What does "external graining" look like?
3. Internal graining is "worse" than external because it can make a diamond hazy, right?

Thanks!

 

[Texas Leaguer]

@lovedogs,
Graining is certainly one of the lesser understood quality factors. And like other quality factors, impact on light performance is a matter of degree. A stone can have some graining without a significant impact on performance. So, seeing the stone and evaluating it in different lighting environments will be the key.

1. Yes, graining can appear as streaks, either internal or external
2. External graining can easily be confused with polish lines
3. Internal graining is that which is confined to the interior.

GIA has found (2021 study) that strong fluorescence alone is not normally the cause of transparency issues (haziness). It is usually one or more inclusion types or structural defects in conbination with strong fluoro that accounts for haziness. The strong fluourescence may accentuate the problem.

Garry has been very vocal about the way graining is reported at GIA. He may have a different take. @Garry H (Cut Nut)