A property of materials that have different refractive indices.
La birrefringencia del cristal se observó al pasar la luz a través de él, creando un efecto hermoso.
The birefringence of the crystal was observed when light passed through it, creating a beautiful effect.
La birrefringencia del cristal permitió observar los diferentes colores bajo la luz.
The birefringence of the crystal allowed us to observe the different colors under the light.