What is proven when a diamond has a flash effect?

When a diamond has a flash effect, it means that the stone is able to reflect and refract light in such a way that it creates a quick and intense sparkle or flash of light. This effect can occur when a diamond is moved or tilted, causing the light to bounce off the facets and create a beautiful burst of brilliance.

The flash effect is a highly desirable characteristic in diamonds, as it adds to the overall beauty and appeal of the stone. It is often used as a quality indicator for diamonds, as stones with a strong and consistent flash effect are considered to be of higher quality and value.

The flash effect can be enhanced by the cut of the diamond, with well-cut stones generally exhibiting a more pronounced and dazzling flash. It is important to note that the flash effect is different from the overall sparkle or scintillation of a diamond, as it specifically refers to the quick and intense bursts of light that can be seen when the stone is moved in different directions.