Historically, ultramarine blue was made by grinding down the semi-precious stone, lapis lazuli.
For cosmetic manufacture, however, ultramarine blue is manufactured in the lab. Kaolin (China) Clay, sodium carbonate and sulpher are mixed together and heated in a kiln to get the characteristic blue shade.
The "raw" blue is then treated to remove impurities.
If you work with Ultramarine Blue, please note that the color can develop a "rotten egg" smell due to the presence of sulphur. This smell develops if the pH is above 6. To eliminate, keep the pH below 6 or add an acid resistant, and keep your pH above 6.5.
⚠️California Prop 65 Warning
⚠️California Residents: Warning: this product MAY contain trace chemicals (<10ppm Lead (Pb); <2ppm Arsenic (As); and <2ppm Mercury (Hg) listed by the State of California under the Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65) as being known to cause cancer, birth defects or other reproductive harm. The level of such chemicals complies with all Federal requirements under the Food, Drug and Cosmetic Act for safety and effectiveness. Please refer to the product Certificate of Analysis (COA) in the documents section.