How can I make nice looking gemstone/diamond material?

I’m working on a project for a client which involves visualizing jewellery.

I’m just a bit stuck on how to make the diamond mateial look realistic.

I feel like updating the reflection map might help, but I also think that rending the backfaces would also help.

They are looking like this:

How can we make it look more like;

I’ve set up a playground example to show what we are currently doing:

Example Playground

It’s worth searching the forum for this topic as there’s been a bunch of great discussions and work shared about this exact topic.


But there’s more …