The newly independent company, to be called Diamond Innovations, manufactures synthetic diamond and cubic boron nitride crystals used in drilling and related industrial activities.
Terms of the deal were not disclosed.
The company is based in Columbus, Ohio, but also has a manufacturing facility in Dublin, Ireland.
Brian Ramsey, a Littlejohn managing director, led the deal.
Tanya Fratto will continue as chief executive officer of the company.
Littlejohn was formed in 1996 when its founder, Angus Littlejohn, left New York buyout firm Joseph Littlejohn & Levy (now called JLL Partners).
The firm recently agreed to acquire a majority stake in technology testing company Wyle Laboratories. In 2002, the firm bought senior debt in PSC, a maker of bar-code scanning equipment that filed Chapter 11 bankruptcy.