Looking for product to cast gems

[jTw1n]

I am looking for a product with which I can create colored semi opaque gems to create glowing gems with a back light from an led. I plan to make a mold of some shapes for the gems and just need a suggestion for a good easily colorable material to cast the molds. Here is the look im shooting for.Thanks for the help.

 

[exoray]

Platinum silicone and Smooth-On clear urethane...

Alumilite clear would be my second choice... You can also use tin cure silicone but I have found platinum works better for clear resin...

 

[jTw1n]

Thank you for the quick reply.