Religious symbols can be so overused that they loose their apparent value. Sometimes we have to take a moment and reconnect to all that the symbol represents. In this scene, our symbols have lost their true value and are being sold as antiquities. Hence the messenger in the reflection who has come to restore these items to their true worth, i.e., to redeem them - an important Christian theme.
The original intent was to experiment with the mental ray misss_physical subsurface scattering materials on the gemstones and amber-like rock material. When the experimenting was over, I was left scratching my head for a scene where religious icons from different time periods would make sense. Hence, the final scene you see above.
IBL environmental reflections went screwy with final gathering turn on. You could see secondary environmental reflections in the angel despite best efforts. And since render times were climbing with final gather (FG) and global illumination (GI) on, I turned FG/GI off and used a number of object specific lights to compensate. Ideally you want few lights and realistic illumination, but in this simple scene the investment in bounce illumination was not warranted.
Final mental ray rendering time at double resolution (1440x1094) was 1hr 12min on a P4 2.4 machine.
Most lights are MR physical lights. The Celtic Cross is just planar projections onto polygon faces.