Colon usage check with example
The Chicago Manual of Style (mine is 13th ed) says this for Colon (section 5.74).
The colon is used to mark a discontinuity of grammatical construction greater than that indicated by the semicolon and less than that indicated by the period. It may thus be used to emphasize a sequence in thought between two clauses that form a single sentence or to separate one clause from a second clause that contains an illustration or amplification of the first.
Your usage seems correct according to the CMoS paragraph.