HAND DRILL ENGRAVING
The tools that are used to engrave this way are rotating Diamond, Stone and Rubber Burs which are fitted in the Handpiece of an electric drill either by tightening a Chuck or by Twisting the Handpiece to open & close the Chuck Release.
These tools can be used to create surface effects on Glass and Crystal i.e Surface Engraving
You can also cut deeper into the glass to create the Illusion of 3 Dimensions which is known as Intaglio Engraving (This is dependant on the thickness of the Glass)
The use of a Handpiece is often called 'Flexible Drive Engraving' Which refers to the type of Drill typically used, which has a flexible drive shaft running from a Pendant Motor, but other types of Electric Drill can be used.
I use both Flexible Drive and Electric Hand Drills to Engrave.
I am used to calling my Drill a Handpiece but that is a result of using my Dental Drill for 32 years.