Scintillation is a product of motion. It requires movement of the diamond, the light source, or the eye of observer in order to produce sparkle. A key component is dynamic contrast within the diamond which creates an on/off effect among the facets.
What attracts most people to diamonds is the snap, crackle and pop of the scintillation of a diamond. That is why most fine stores are very smart to intall perfect lighting over their diamond cases to bring out this in the diamond. Notice in most of the ads for diamonds these days has them on a turn stile as the diamond puts on a show. A high performance diamond of ideal cut under correct lighting will cause the customer to gasp. It’s a wonderful sight.