Smallest neodymium magnets

What is the smallest size that neodymium magnets can process?

Smallest magnet size that neodymium magnet manufacturers can generally produce; Round magnet: diameter 0.5mm, thickness 0.4mm or so. Ring magnets: diameter 1.5mm, hole 0.4, thickness 0.4mm or so Square or block magnets: length and width 1mm, thickness around 0.4mm...