You may be looking for reflection or refraction.
Reflection is the phenomenon of light bouncing off an object; refraction is the phenomenon of light bouncing around inside a gemstone, for example, and then bouncing back to the eye of the beholder.
A light-half, I believe.
The ray of light that hits a mirror is called the incident ray.
reflection
The diamond you reference is also known as the Koh-i-noor. You can read more about it, below.
An incoming light ray before it hits a mirror is called an incident ray.
The process of cutting a diamond is called diamond cutting, where the rough diamond is carefully shaped and polished into a gemstone. The goal of diamond cutting is to enhance the stone's brilliance, fire, and sparkle by creating facets that reflect and refract light. Skilled diamond cutters use precision tools and techniques to create the desired cut for the diamond.
When light hits the diamond crystal, it enters and is refracted within the diamond due to its high refractive index. The facets of the diamond act as mirrors, reflecting the light internally and causing multiple reflections. When the diamond is moved slightly, these internal reflections change, creating a brilliant play of light known as dispersion and scintillation.
The "Crown of Light" diamond, is a diamond only sold at Diamond International. It is very beautiful.
light bends when it hits the lens....this is called refraction
Reflection.
specular reflection.
In complete darkness, devoid of any light -- deep within a cave, for example -- no diamond will 'shine'. Every diamond, however, will reflect and refract ambient light, even if it is simply moonlight or starlight.