Why was natural ultramarine so precious?

Crushing is only one step

Grinding a blue rock changes its particle size, but does not automatically remove its other minerals. Separation and binding solve different problems: obtaining useful blue particles, then making them work as paint. The finished colour alone cannot establish its exact origin or price.

From stone to paint

1. Select lapis lazuli

   Lazurite gives this rock its rich blue.

2. Prepare the pigment

   Processing separates the useful blue particles.

3. Mix and paint

   A binder turns pigment into usable paint.