I offer burnishers made of agate or hematite stone. Unlike metal burnishers, stone burnishers do not require oil to polish well. You can then better see the progress of its polishing.
Hematites are softer stones than agates (but nevertheless harder than standard steels). They may polish a little better, but are less durable than agates.
Precision burnishers are available in 3 main shapes:
Simple conical shapes: the round version is versatile and easy to use. The pointed version is the most precise of my burnishers, to be reserved for micro details.
Truncated shapes, based on a reworked pointed cone shape. The flat end version is mainly used to make fine white lines, especially in mezzotint. The truncated versions 1mm or 2mm to make precise gradients.
The curved shapes, very versatile and easier to use than the truncated shapes. Better polishing than the basic conical shapes. The 2 agate versions are quite close, the "wide and very curved" hematite version is much less precise
The maxi burnishers are available in 3 versions
The curved maxi hematite burnisher, to rough out gradients.
The extra large maxi hematite burnisher. The shape of the stone allows for very efficient burnishing, and the angles are relatively precise
The maxi agate burnisher, smaller than the hematite version, has the same efficiency qualities as the extra large hematite version, but much more precise