In this composite shot, each hand and the diamond were captured separately. Here is the lighting setup explanation for each photograph.
Diamond:
I used two Profoto D1s with blue and magenta color gel attached to them. I placed the strobes below and above the diamond with a 10-degree Profoto grid to focus the light. The grids helped me bring sparkles and make hot lights to the diamond.
To create a glowing effect, two Profoto D1s and strip softboxes with blue and magenta color gels attached inside the softboxes and were placed behind the diamond and closed to the background. By feathering the lights, I produced a nice gradient from blue to magenta on the background.
Hands:
The lighting setup for both hands was the same. I only replaced the color gel for each hand.
For the key light, I used Profoto D1 with a 3/4' RF softbox.
A Profoto D1 with strip softbox and a blue/magenta color gel attached inside the softbox was placed slightly behind the model's hand to produce rim light.