Cerium oxide can be a very confusing topic for many people as there are so many variations out there and so much conflicting specifications.
It boils down to finding out how much actual cerium oxide is in your mixture. Oftentimes manufacturers will list cerium content as how much of standard rare earth material percentage the cerium is.
Let's say you have a mixture that has 80% rare earth materials and 20% of a bunch of other junk. If cerium oxide is 90% of the rare earth material, then many manufacturers will list cerium content as 90% when it is actually closer to 70% of the entire mixture. This can cause a lot of confusion when it comes to using your cerium.
We try to list the actual cerium content percentage of the entire mixture for our ceriums so you're comparing apples to apples. The more actual cerium you have, the brighter the polish will be.
Particle size comes into play when you're working with clarity of the polish versus how quickly you accomplish the polish. The higher the particle size, the faster the polish, the lower the particle size, the better the polish.
These two pieces: percentage of cerium and particle size, will compliment one another and go up and down depending on the particular cerium. It's generally a balancing act to keep the polish as fast as possible and maintain as clear a polish as possible.