Diamond with blue sparkle/fire

[ElizabethR]

what does it mean when a diamond flashes blue? I was looking at a cross pendant and the stone second from the top seemed to flash/sparkle blue while the others around it didn't. Can anyone shed light on this for me?

Thanks,
Elizabeth

 

[kenny]

3 things just happen to be in the position so the light was dispersed into blue ... you, the diamond, and the light.

Move any of the 3 slightly and the blue will turn to green, then to yellow they to orange, etc.

 

[yssie]

A bit off-topic, but an interesting series of letters discussing seeing green: https://www.pricescope.com/journal/letter_editor_australian_gemmologist