Laser inscription, refers to a very small graphic or text being inscribed on the girdle of a diamond. The inscription is commonly a brand name, certificate number with laboratory name and/or a romantic message. The inscription is only visible with a jeweller's loupe, and even then can be difficult to read.
Prior to laser inscription, sealing diamonds in plastic packets was a popular way to prove that the diamond matched the certificate. Nowadays, a grading laboratory can laser inscribe the certificate number on the diamond's girdle, providing even more security over the sealing method.
However, it should be noted that laser inscription is not entirely fool proof. As Fred Cuellar explains:
Equipment used to laser inscribe diamonds can cost up to US$300,000. This is reflected in the extra cost charged by grading laboratories to do laser inscriptions. Manufacturers of laser inscription equipment include Sarine and PhotoScribe.
Real Life Examples
Below are some examples of laser inscription:
As you can see, some laser inscriptions can be difficult to see, especially under frosted girdles.
Where To Get Your Diamond Laser Inscribed
Most international labs such as the GIA, EGL and HRD have laser inscription services. In Australia, the DCLA offers laser inscription services.