The OEM and some of our BLUETEC replacement lamps have a gold coating which acts as a reflector. This gold coating wears out over time, making the lamp less effective. We are working hard to switch all of our lamps to the new white coating which is more durable and provides better curing results. This white coating is actually a AL2O3 ceramic which has a far better temperature resistance than gold. The aluminum ceramic coating will last longer and effectively remains unchanged during the lifetime of the lamp. This results into a constant, more efficient light output which makes BLUETEC lamps the overall better product. Speedmaster 74 Speedmaster 102 Heidelberg MO