Seeing dark spots in a diamond can be a scary thing, especially if it’s in your newly purchased internally flawless diamond! What other than an inclusion might cause dark spots in a diamond?
The only way to tell for sure is a visual inspection. Let me tell you how you can test the diamond if you had it in hand. Dark spots, if not due to an inclusion can be one of three possibilities; (1) obstruction; (2) light leakage; or (3) prong reflection.
An easy way to rule out head shadow/body obstruction is by a technique I learned from Gary Holloway and that is to make a pinhole out of a white piece of paper and view the diamond through that tiny hole. If the dark spots are still visible, then you know that it is not obstruction.
You can tell whether a diamond is leaking by placing the ring over a bright-colored object. Now one of the best things is to find a red piece of clothing. If you can see red through the diamond, in particular if the dark spots turn to red in color, then you will know that the diamond is leaking.
It is also possible for those two dark spots to be reflecting the image of the prongs. The dark spots were visible in the same place even when the picture was taken at a different angle, which reduces the chance that the dark spots are obstruction problems. On the other hand, one of the dark spots disappears in the picture where there is slight tilt. Unfortunately, the only way to tell whether these dark spots are prong reflections is either with a loupe or an ASET. With a loupe, you can simply put your finger next to that prong and see if the reflections are coming from that direction by looking to see if you can see the color of your skin. If you have dark skin, then it may be better to find something else like a toothpick that you can put next to the prong. On an ASET, a prong reflection is obvious because it will look grey and dull if you are viewing it under proper lighting conditions.
The takeaway from this is that if you are in the market for a fancy cut diamond, then you need to purchase from a vendor who supplies ASET images. You also need to spend a bit of time learning to interpret these images. It isn’t difficult at all, and for most people, it comes down to finding a diamond with minimal greens, and a pattern that you like with a predominance of red and a even distribution of blues. The problem with buying online is that I don’t know of a vendor that provides ASET images throughout the tilt angles. One way you can protect yourself better is to purchase an AGSL graded diamond as the AGS cut grading system is better tailored to fancy cut diamonds. Apart from considering the light performance from a face-up view, AGSL will judge how the diamond performs throughout the tilt angles as well.