Brooklyn, NY — The Three Diamond Door, an American restaurant at 211 Knickerbocker Avenue in Brooklyn, received a Grade B following a March 2026 health inspection, with a score of 23 — placing it near the upper boundary of the B range and four points from the Grade C threshold.

The inspection was conducted on 2026-03-28. Data was released by the New York City Department of Health and Mental Hygiene (DOHMH) on 2026-03-31.

What Inspectors Found

Inspectors documented one critical violation during the visit:

  • Code 04A: A Food Protection Certificate (FPC) was not held by the manager or supervisor of food operations.

Under NYC Health Code Article 81 and DOHMH regulations, at least one certified food protection manager must be present and responsible for food handling operations during business hours. The Food Protection Certificate is obtained through a city-approved food safety course and examination. Its absence at the supervisory level is classified as a critical violation because certified oversight is considered a foundational safeguard against foodborne illness risks.

No non-critical violations were recorded during this inspection.

Food Safety Context

The FDA Food Code and NYC Health Code Article 81 establish the requirement for trained, certified supervision in food service environments. A Food Protection Certificate ensures that the person overseeing food operations has demonstrated knowledge of safe food handling, temperature control, cross-contamination prevention, and sanitation protocols.

A score of 23 falls within the Grade B range but sits near its ceiling. Under NYC's grading system, restaurants scoring in the upper portion of the B range carry a greater margin of risk relative to those near the Grade A boundary. The restaurant was not closed as a result of this inspection.

Inspection History

The Three Diamond Door's recent inspection record shows variability in scores:

  • 2024-09-21: Score 13 (Grade A)
  • 2023-06-16: Score 17
  • 2022-03-24: Score 7 (Grade A)

The restaurant previously held Grade A scores in both 2022 and 2024. The current score of 23 represents a notable increase from its most recent prior inspection.

Understanding NYC Restaurant Grades

New York City's letter grade system is based on inspection scores assigned by DOHMH:

  • Grade A: 0–13 points (lowest number of violations)
  • Grade B: 14–27 points
  • Grade C: 28 or more points

Lower scores indicate fewer or less severe violations. A score of 23 places The Three Diamond Door in the upper third of the Grade B band.

Consumers can look up inspection records for any city restaurant through the DOHMH's NYC Restaurant Inspection Results database at nyc.gov. Records include violation details, scores, and grade history for all inspected establishments.

More About This Restaurant

View the full inspection history for The Three Diamond Door including all past inspections, violations, and grade changes.