One of our readers sent in a very interesting question after reading about an unusual comment found in a GIA grading report. The question he asked was “What is an etch channel? I found this being plotted on a GIA certificate from one of my shortlisted VS2 diamond. Could you kindly shed some light on what this is?”
An etch channel is basically a hollow tunnel that forms at the diamond’s surface and penetrates into its body. Its appearance can be very similar to inclusions caused by an internal laser drilled treatment but they could also exist in different forms such as parallel lines or irregular worm-like structures.
Photographs depicting the different shapes and appearances of etched-channels
Scientists believe etched channels are formed when diamonds are being transported from the Earth’s mantle to the surface. During that journey, high temperature fluids can sometimes “eat into” the stone’s crystalline structure. As seen above, this leaves natural marks that appear in a variety of interesting figures.
Depending on the depth of the etched channel/s, it doesn’t make economical sense for the cutter to remove excess weight from the rough just to polish out the channels.
Since etch channels are surface breaking inclusions, the age old question of reliability and durability will probably be a cause for concern for many shoppers. The key to answering this question is to look at the clarity grade of the stone.
Generally speaking, for diamonds with VS2 clarity or better grades, they shouldn’t have durability issues with them. Rest assured that when the labs perform an actual grading, they do take into account durability risks and severity of the inclusion/s before assigning a rating.
Is this SI2 diamond eyeclean and safe for purchase?
For diamonds with lower clarity grades within the SI1-SI2 ranges, it is best to visually inspect the stone for eye cleanliness or have a trained gemologist eyeball the stone on your behalf.
My personal recommendation is to avoid etch channels that are found on the pavilion side for practical reasons. If dirt and muck get trapped or lodged inside the tunnels, it can make cleaning very tough once the diamond is mounted on a setting.
To see photographs and understand other types of commonly found inclusions in a diamond, this list here should interest you.