Do diamonds shine or they reflect?

The short answer is that they are expertly cut and polished to maximize the diamond's natural brilliance. ... Diamonds get their brilliance from three things: reflection, refraction and dispersion. Reflection is the light that hits the diamond and is immediately bounced back up, giving it an instantaneous shine.

Do real diamonds shine without light?

Diamonds are Cut in such a way to maximize light, draw it in, and reflect it out so it sparkles like a billion stars in the sky. ... So the answer to the question is “No, Diamonds do NOT Sparkle in the dark! “ They need light (which is why Jewelry Stores have tons of it) and they need a Good Cut to really bring it out.