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What is Diamond Paste?

By Devon Pryor
Updated: May 17, 2024

Diamond paste is a type of polishing compound made from finely ground or powdered diamond particles, and some kind of liquid, usually water based. Diamond powder itself is simply paste without the water or other liquid binding agent. It may come in a syringe for more exact application, or even come in a small pump-spray bottle. Some manufacturers produce pastes with different sized grits in specific colors. Color coding can facilitate selecting the proper size of grit for the surface that is to be polished.

This compound can be used to polish or sharpen a variety of tools and surfaces. Diamond paste is recommended for finely polishing various metals, including metal blades and other metal surfaces. In the case of a metal blade, of course, the paste not only polishes the flat surface of the blade, but also finely sharpens the cutting surface. Diamond paste is appropriate for use on ceramic, glass, and mineral surfaces. It can also be used to clean surfaces made out of the aforementioned materials.

Using diamond paste to sharpen a metal tool is considered the best way to get the sharpest edge possible. When used in this manner, it may also be called diamond lapping paste, which is available in a number of different types with different sized grits. The size of the grit is measured in microns, so a one micron diamond paste is a paste with grit particles one micron in width. A micron is equal to one millionth of a meter or 0.00003937 inches. The smaller the grit, the more finely sharpened the edge will be.

Diamond paste may be applied with a polishing cloth. A product called diamond polishing extender fluid can be used to help with evenly distributing the paste on the polishing cloth. This, in turn, ensures a more even polish. Diamond paste may also be used with a tool called a strop, though this is less common. A strop is a hand-held, flat, paddle-like tool, which is made from synthetic material. The strop is flat and even, perhaps with rounded edges. The polishing substance is applied to the blade of a tool and rubbed against the flat surface of the strop.

Materials that are difficult to polish may require a specific type known as polycrystalline diamond paste. This differs from the typical monocrystalline paste in that the diamond grit particles are of a different shape. Monocrystalline grit particles in are flatter in shape and have fewer cutting edges, and these edges are longer. The polycrystalline particles are multifaceted, and spherical in shape. This simply means that the particles in a polycrystalline paste have more edges.

More cutting edges on the diamond particles create a more abrasive grit than that of other pastes. Diamond paste with polycrystalline grit might be used to clean a surface, then is followed by one with a monocrystalline grit for more fine polishing.

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Discussion Comments
By anon132521 — On Dec 07, 2010

I wish to know the grit to use on an already shiny surface of a tungsten-carbide bezel of a Rado DiaStar. I just wish to remove some discolorations. Thanks a lot. JunM.

By anon44089 — On Sep 04, 2009

what type of diamond paste would I use to get a shine on aluminum that I could shave in? Extreme mirror finish. Item in question: the forks on my motorcycle. I already have them sanded, and polished all the way through jewelers rouge. Still not satisfied. Please help if you can. Thank you. Tom W.

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