Diamonds are not magnetic.
Diamonds are made of pure carbon atoms arranged in a very strong and rigid crystal structure. This structure does not allow for the presence of unpaired electrons, which are necessary for a material to exhibit magnetic properties.
In contrast, materials like iron, nickel, and cobalt are magnetic because they have unpaired electrons that can align themselves in a magnetic field.
This means that a magnet will not attract a diamond, and a diamond will not be able to attract other materials.