About a year later, in fall 1941, Liddicoat helped develop the Diamolite, and also published, alongside Robert M. Shipley, his first article for Gems & Gemology; "A Solution to Diamond Color Grading Problems".
[citation needed] After serving in the United States Navy during WWII, he returned to GIA as Director of Research in February 1946.
[4] Exactly a year later, in April 1953, he officially introduced the GIA diamond grading system as part of a new educational class in New York.
[citation needed] In 1970, Liddicoat launched a series of extension education classes in Israel taught by Glenn Nord, making GIA's first global outreach.
He received the 1976 American Gem Society's Robert M. Shipley Award, and created the GIA Research Department under the leadership of Dr. D. Vincent Manson.
A central feature was the D-to-Z color grading system for faceted colorless to light yellow diamonds—the vast majority of diamonds seen in the trade.
Subsequently, many of these students asked GIA to set up a procedure whereby they could submit their grading worksheets, and eventually the diamonds themselves, for an independent assessment.
In 1942, as Director of Education, Liddicoat developed an intensive one-week lab class that was launched at the American Gem Society (AGS) Conclaves in Philadelphia and Chicago.
When Robert M. Shipley set up his Los Angeles laboratory in the early 1930s, the Institute's resources were devoted to identifying gems and to documenting the properties and techniques that would aid in their identification.
His objective throughout instrument development at GIA was to provide jewelers with practical tools that could help them in the day-to-day operation of identifying gemstones.
By the 1970s, the GIA Gem Trade Laboratory staff was examining large numbers of gemstones, including the grading of diamonds and the identification of colored stones and pearls.
Sensing the need for a group of scientists who would focus on the many emerging technical challenges in gemology, Liddicoat formally established the current GIA Research Department in 1976.
In June 2000, a life-size bronze statue based on Liddicoat was created by staff member Michael Clary, placed at the entrance of GIA Carlsbad.