One way of doing this would be to create a looping animation of one diamond with a lens flare applied on top and animated to create the “sparkle”. Once you have that you can precompose and duplicate that comp as many times as you need to create a texture for the face of the letters/numbers. If you need just 3d looking text with no camera move, you can create the text in AI or PSD, import it in AE, and build the face of the letters using the diamond texture. If you need volumetric letters that will react to camera moves I recommend looking into ShapeShifter AE or Zaxwerks Invigorator Pro. You can then create the depth of the text using those plugins and match the position behind a 3d layer that has the same text build out of the diamond texture.
Tudor “Ted” Jelescu
Senior VFX Artist