@rauliruegas I'm afraid I do not understand your last post. All I can say for sure is I now have cartridges with diamond, boron and cactus spine cantilevers and all three are fine cartridges. I can say from a tracking performance perspective the cactus spine can handle the highest groove velocities. It is also a thing of beauty. From a sonic perspective all three sound remarkably similar so It might just be an all roads lead to Rome situation.
@lewm From a stylus perspective I do not think there is any difference between a natural and synthetic diamond both can have various levels of inclusions. I have looked at some styluses that were black with contamination and these styluses are going to wear out faster and are more likely to damage grooves. Again there is a level of quality and selection. The more expensive cartridges tend to get much cleaner styluses. I have a very inexpensive Ortofon 78 RPM cartridge. The stylus is spherical and swaged to a brass ferule (not naked). It is poorly polished and very dark. Another interesting attribute which anyone can see without a microscope is the diamonds of the more expensive cartridges are much smaller lowering the effective mass of the assembly. Less expensive cartridges using an aluminum tube for a cantilever with have the diamond pressed into the crimped end of the cantilever with a lot of excess material while the more expensive cartridges use much lighter mountings. With every cartridge made there are various levels of quality. The more expensive cartridges are more consistent but you can still get a dud. And, you had better take a lot of food down there with you:-)))