Crime Rate in Diamond Bar, CA (2025)

Diamond Bar has a Crime Index of 80 out of 100 (grade B — safe) for 2025, based on FBI-reported violent and property crime rates relative to other US cities. That ranks it #40 of 175 cities in California by reported crime. Reported crime is not the same as actual crime. Research on the gap between crime that occurs and crime that gets reported to police — often called the "dark figure" of crime — estimates that roughly 40% of violent crime and about a third of property crime go unreported each year. Every index built on official statistics, including this one, necessarily undercounts real crime. That gap is exactly why homicide — the offense with the smallest dark figure — anchors the calculation instead of a more commonly reported but less reliable category like theft.

A "Safe" grade means Diamond Bar's severity-weighted crime rate falls in the 75–87 range on the Crime Index, out of a national distribution of every city we track for 2025. Grades are calibrated against the national distribution of every area we track for the same data year — they describe an area's relative standing, not an absolute promise. A "Very safe" grade means an area sits among the lowest-crime places in the country with usable data, not that nothing ever happens there.

No. National research on the dark figure of crime estimates that roughly 40% of violent crime and about a third of property crime are never reported to police, so any index built on official statistics — including this one — measures a floor on real crime, not a ceiling. That's part of why the index leans most heavily on homicide, the category with the smallest reporting gap.