How do you identify a surface reaching inclusion?

[ajoh3142]

Greetings All - How does one identify a surface reaching inclusion, or an inclusion that "breaks the surface" of the diamond. I see diamonds that have feathers at the edge of the stone that come up to the top of the facet and appear white, but they don't "open up" or create a break in the stone when viewed with a loupe and turned away from the light. In other words, there is no break in the facet, but the inclusion is just below the facet - is what I'm describing surface breaking?

 

[whatmeworry]

Read this article by coatimundi

https://www.pricescope.com/journal/diamond_feather_inclusions_durability_risk

one way is to look at reflected light off the facet and if you see a shadow line, then it's the feather breaking the surface.

 

[Rhino]

I have a brief example in the video on our home page in the welcome video. What "whatmeworry" wrote is right though. The diamond must be examined under a microscope in reflected light (as opposed to darkfield illumination) to examine the surface of each of the facets.

 

[whatmeworry]

You may not be able to see it open up or the shadow lines because they may be very slight. (don't expect to see the Grand Canyon!) Another way to tell is if the feather has an abrupt straight edge to it. That's where it's breaking the surface. This is a GIA SI2 and two feathers are breaking the surface. I drew straight lines to show you where they break the surface.

 

[Rhino]

Noble attempt wmw. I'm pretty sure I have a shot of this around I'll post tomorrow to demonstrate how it looks under the microscope. It's 100x easier to see under the ms.

 

[kenny]

In animals you can look for blood.

 

[ajoh3142]

Thanks for all of the information. I have taken another look at the stone. I haven't used a microscope, but a 10X loupe. When I turn the stone so the top of the facet where the feather is appears dark or shadowy, I can't find even the minutest line, indentation or anything else in the facet surface. Now, on the other hand, on another side of the diamond there is a very small straight opaque line, which I think would be considered a needle. When I loupe that using the same technique, I see a very light and shallow opening in the surface. What do you all think?

 

[ajoh3142]

Update - I read the article wmw linked to in his post. The feather in the diamond I am describing looks exactly like the feather in the diamond pictured - same area, same color, same type of jagged nature - ONLY the feather in the diamond I am describing in probably only 1/3 of the length of the feather pictured in the article. Again, no shadow line and trust me I've looked hard.

 

[whatmeworry]

It's really hard to say without seeing the diamond in person. Maybe it doesn't reach the surface. Maybe you need a microscope and better lighting to see it. Is it graded by GIA? According to the article, if it's surface reaching then GIA will classify it as a feather.

 

[ajoh3142]

Thanks for the information. Rhino, did you come across the picture you were going to post? Thanks again.