Cosmetic Color Index (CI) Numbers: A Complete Guide for Precise Selection & Communication

Introduction: The Universal Language of Color

A lipstick manufacturer in Shanghai. A pigment supplier in Hangzhou. A regulatory agency in Brussels. They all need to talk about the same red pigment — precisely, unambiguously, across languages and borders.The Colour Index (CI) number is that universal language. Developed and maintained by the Society of Dyers and Colourists (UK) and the American Association of Textile Chemists and Colorists (AATCC), the CI system assigns a unique identifier to every commercially available pigment and dye.This article explains the CI system for iron oxide pigments — how to read CI numbers, why they matter, and how to use them for precise communication with suppliers, formulators, and regulators.

Part 1: What Is a CI Number?

A CI number is a five-digit identifier (sometimes with a letter prefix) that uniquely identifies a colorant by its chemical structure, not its trade name or commercial designation.

Example: Iron oxide red is always CI 77491 — regardless of whether it comes from China, Germany, or the United States, and regardless of the supplier's trade name ("Red 304," "Lip-Red 100," etc.).

Key advantages of the CI system:

· Universal: Recognized in all major cosmetics markets worldwide

· Unambiguous: One CI number = one chemical substance

· Regulatory: Most cosmetics regulations reference CI numbers

· Supplier-independent: Enables like-for-like comparison across suppliers

Part 2: CI Numbers for Iron Oxide Pigments

Iron oxides used in cosmetics and food have three primary CI numbers:

Additional CI Numbers for Iron-Based Pigments:

· CI 77489: Iron oxide (low transparency — less common)

· CI 77480: Iron hydroxide (rarely used)

· CI 77510: Ferric ferrocyanide (iron blue — different chemistry)

Important: CI numbers identify the chemical, not the grade. Both industrial-grade and cosmetic-grade CI 77491 are chemically the same. The difference lies in purity, particle size, and documentation — not the CI number.

Part 3: How to Read and Understand CI Numbers

The Structure:

CI numbers for inorganic pigments (like iron oxides) generally fall in the 77,000 range. Organic pigments have different ranges (e.g., CI 10000-73999 for dyes, CI 74000-77999 for organic pigments).

What CI Numbers Do NOT Tell You:

· Particle size distribution

· Surface treatment (e.g., dimethicone-coated vs. uncoated)

· Purity level (heavy metals)

· Batch-to-batch consistency

· Price or commercial grade

Therefore: CI number alone is insufficient for product specification. Always combine CI number with detailed technical data.

Part 4: CI Numbers in Regulatory Documentation

European Union (EU)

EU Cosmetics Regulation (EC) No 1223/2009 lists colorants by CI number in Annex IV. Iron oxides appear as:

· CI 77491

· CI 77492

· CI 77499

The regulation specifies purity requirements and permitted uses.

United States (FDA)

FDA uses common names rather than CI numbers. 21 CFR 73.2250 lists "Iron oxides" as a category. However, CI numbers are widely used in industry communications and specifications.

China (IECIC)

China's Inventory of Existing Cosmetic Ingredients (IECIC) references CI numbers. Iron oxides are listed under their CI numbers.

Japan

Japan's Positive List system references both CI numbers and Japanese names.

Regulatory note: Different jurisdictions may use different naming conventions for the same CI number. Always verify the local regulatory name for your target market.

Part 5: CI Numbers vs. Other Identification Systems

Part 6: Practical Applications — Using CI Numbers in Your Work

For Procurement Professionals:

Always specify CI number in your purchase orders. Example: "Iron oxide red, CI 77491, cosmetic grade, dimethicone-treated, D50 0.5-0.8 μm."

A specification without a CI number is ambiguous. A specification with a CI number is universally understood.

For Formulators:

Use CI numbers in your formulation records to ensure reproducibility across different suppliers. When a supplier changes, the CI number helps you find a replacement with the same chemistry.

For Regulatory Affairs:

CI numbers are the primary reference for colorant compliance in most global regulations. Your regulatory submissions should always include CI numbers.

For Quality Control:

CI numbers are part of your incoming inspection criteria. Verify that the received pigment matches the CI number on your specification.

Part 7: Common Mistakes and Misconceptions

Mistake #1: Assuming that the same CI number from different suppliers is identical.

Reality: CI number identifies the chemical, but particle size, surface treatment, and purity can vary significantly.

Mistake #2: Using CI number alone for regulatory compliance.

Reality: Compliance requires CI number PLUS purity data PLUS intended use information.

Mistake #3: Confusing CI 77491 with CI 77499 or other CI numbers.

Reality: Each CI number represents a distinct chemical. Mixing them up causes formulation failures.

Best practice: Always specify CI number, grade (cosmetic/food/industrial), and key performance parameters together. No single identifier tells the complete story.

Part 8: How Hangzhou Hangyan Technology Uses CI Numbers

At Hangzhou Hangyan Technology, we use CI numbers as the foundation of our product identification system:

· Every product: Identified by CI number plus grade designation (e.g., "HY-CI77491-C" for cosmetic-grade CI 77491)

· Every COA: Includes CI number as primary identifier

· Every regulatory package: Organized by CI number for easy cross-referencing

· Every customer specification: We ask for CI number first

Our product families by CI number:

Hangyan commitment: Our CI number-based product system ensures clarity and prevents confusion. When you order CI 77491 from us, you receive CI 77491 — not a blend, not a substitute, not a "similar" pigment.

Part 9: Quick Reference Card

Iron Oxide CI Numbers for Cosmetics & Food:

· CI 77491 — Red iron oxide (Fe₂O₃)

· CI 77492 — Yellow iron oxide (FeOOH)

· CI 77499 — Black iron oxide (Fe₃O₄)

By blending these three, you can achieve:

· Browns: CI 77491 + CI 77492 + CI 77499

· Oranges: CI 77491 + CI 77492

· Burgundies: CI 77491 + small amount CI 77499

· Nudes: CI 77491 + CI 77492 + white base (titanium dioxide)

Conclusion: Speak the Universal Language of Color

In a global industry with multiple languages, regulatory systems, and commercial names, the CI number is the one identifier everyone understands. It bridges the gap between suppliers, formulators, regulators, and quality teams.

Using CI numbers precisely — and understanding their limitations — is a mark of professional competence in the color industry.

At Hangzhou Hangyan Technology, we speak CI number fluently. When you need CI 77491, CI 77492, or CI 77499 — in cosmetic, food, or industrial grade — we deliver exactly what you specify.