Lani, we were discussing at one point the possibility of using an agitator like an ultrasonic bath, but instead of a cleaning solution, using a combination of sea salt and sand. Then exposing to a higher dose of UV light. It may take a while, but I think the results would be pretty spot on.
I was theorizing that the aging of an insert takes place when watch owners actually dove with their watches. So, if they are moving through the water, there is salt and dirt particles passing over the bezel insert constantly. An ultrasonic machine would, in theory, speed up this process.
Finding something like an EPROM eraser, which uses UV light to erase a programmable micro-chip are super cheap and you could fit a few bezel inserts in there at one time. They have a timer on them so it would take some experimenting.