Lorbeer Middle School 501 S Diamond Bar Blvd, Diamond Bar, CA91765 Lorbeer Middle School is a California Distinguished and National Blue Ribbon School serving 731 students from 6th to 8th…More grade in North Diamond Bar. It is a part of the Pomona Unified School District and is located on the corner of Diamond Bar Boulevard and Golden Springs Drive. From 2009 to 2010, Lorbeer's Academic Performance Index score rose 25 points from 810 to 835. Compared statewide, the school's API scores 10/10. Compared against a group of 100 similar schools, the score is 5/10. Its mascot is the Longhorn.