How to Compare Brightness, Patterned Scintillation and Fire in Multiple Diamonds?

[spicyjalapenopopper]

Hello! I have 3 diamonds that I’d like to compare. I saw this video by Good Old Gold on YouTube where he compares the brightness, patterned scintillation, and fire between diamonds. I tried to replicate this but wasn’t able to. How does he achieve the lighting? I know he talks about diffused lighting, spot lighting and a stronger spot light. I tried using a strong flashlight which kinda showed the scintillation but not that well. Is there a special light I can buy? Thank you!