Following these points will enable you to select the optimum ferrite core.
Select the core with the smallest possible inner diameter (this is the most important point).
Make sure the length exceeds the outer diameter.
For effective results, the priority order is (1) inner diameter, (2) length, and (3) outer diameter.
Number of turns of wire
Basically, the effect is proportional to the square of the number of turns of wire.
For frequencies above 300 MHz, do not wind more than 3 turns of wire.
If you use Murata products, the materials make no difference at higher frequencies (above 30MHz).