GIA Knowledge Sessions Webinar - recorded live on September 24, 2020.

Diamond is one of the hardest natural materials on earth, and cutting and polishing it is no simple feat. In recent decades, technological advancements such as laser cutting have greatly enhanced the ease and precision of diamond cutting, but artisans have been polishing diamonds since at least the end of the Middle Ages! How is it even possible to cut and polish this exceptionally hard material? How does human skill unleash a diamond’s brilliance? Learn the answers to these questions and more from GIA Research Scientist Dr. Evan Smith as he covers the history of diamond polishing and shares his own experience cutting diamonds for scientific research.

Read more of Dr. Evan Smith's research:
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Questions answered by Dr. Karen Smit during the live webinar:
Q. What does the 111 mean?
A. 111 is the octahedral crystallographic direction of diamond.

Q. Do inclusions interfere with cleaving clean lines?
A. Yes, sometimes mineral inclusions do interfere. It is best to try cleave the diamond along a plane where there are no inclusions.

Q. Is there any waste from cutting and polishing diamonds? is it used to polish and cut for more diamonds?
A. Some of the smaller diamond particles and diamond dust can be collected and used to embed the scaife with diamonds for polishing. For gem diamonds, there are often diamond offcuts. They can be used to cut smaller stones and melee. If these offcuts have interesting mineral inclusions in them, they can be donated for scientific study ;)

Q. So it rotates by itself?
A. The person polishing needs to rotate the stone into a new direction

Q. When polishing, what mechanism converts the diamond dust back to graphite? Is it due to the heat and pressure of the polishing process?
A. The high temperature of polishing means that it is easier for (metastable) diamond to convert to the form of carbon that is normally stable at atmospheric pressure: graphite

Q. Do the layers in the diamonds affect the color or clarity of the diamond?
A. Sometimes. In the majority of diamonds, the different growth layers are colorless. If the diamond has color-forming defects, such as isolated nitrogen, boron etc, then the growth zones may have different intensities of color. Some diamonds have micro-inclusions that may be incorporated into some growth zones and not into others, and that may impact the color.

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