I have been trying to understand some aspects of the evolution of the Earnshaw spring detent escapement. I have seen references to 'old' and 'new' styles. I found a thread here that suggested that the main difference is the diameter of the roller table. Are there other possible differences? I am wondering if there were differences in the impulse jewel as well? Perhaps some examples not employing an actual jewel? I wish there were more pictures available on the net to study, but most depict only the modern Hamilton, Swiss, and Russian examples. Thanks!