Diamond Files: What They Are, How to Use Them & Why They’re Essential
Diamond files are essential tools for jewellers, horologists, glass artists, and anyone working with hard materials. Whether you're shaping precious stones, refacing clock parts, or sharpening carbide tools, a quality diamond file provides unmatched precision and durability. In this guide, we cover the top uses for diamond files, how they work, and how to choose the right grit and shape for your tasks.
What is a Diamond File?
Diamond Files are manufactured by electroplating diamond onto steel blanks using nickel. The smaller the particles, the finer the grit of the file. This is why diamond files are referred to in grits rather like sandpaper. The higher the number, the smaller the grit and the finer the finish. For example, a 600 grit diamond file will be much finer than a 220 grit.
Why Use a Diamond File Instead of a Traditional Steel File?
Diamond File vs Traditional Steel File Comparison
| Feature | Diamond File | Traditional Steel File |
|---|---|---|
| Abrasive Material | Electroplated diamond grit | Steel teeth |
| Cuts in All Directions | Yes | No |
| Works on Hard Materials | Yes (e.g. carbide, glass, stone) | Limited |
| Typical Grit Range | 120 – 900 grit | Coarse to super fine |
| Longevity | High (especially with wet use) | Shorter lifespan on hard materials |
As you know, traditional steel files have teeth similar to those of a saw blade. The smaller the teeth, the finer the cut of the file, but all these teeth are lined up in the same direction. So this means that with a traditional file, it will only cut in one direction, like a saw. Even when you have a round or half-round file, they still only cut in a forward direction. They don't work sideways or in a circular motion, for example.
In contrast, diamond files don't actually have teeth as such, but diamond grit. This gives diamond files a unique property in that they will work in any direction.
Diamond Files cut in all directions, produce a better finish
The distribution of diamond particles enables the diamond needle file to not only cut in all directions but also produce a much better finish. Therefore, diamond needle files can offer a fantastic abrasive for a variety of applications.
Due to the hardness of diamonds, diamond files can be used on a variety of materials that other abrasives will not have an impact upon.
Diamond Files cut on the pull stroke as well as the push stroke
When you're working in small intricate areas, the diamond file will work on the pull stroke just as effectively as it does on the push stroke. So this may make it slightly easier in confined spaces. It also means, in theory, that it will cut twice as fast as a toothed file of the same grit because it cuts on both the pull and push strokes.
Another huge advantage is the fact that they also work sideways and with a twisting motion.
How to Use Diamond Files
1. Use The Tip Of A Diamond File For Detailed Areas Such As Ring Shanks
You can use the fine tiny points of the files to get into tiny areas. As long as you can move the file in any direction, it will cut and it will file for you. This is particularly useful with a large round 600 grit diamond file or a 600 grit diamond needle file, as it can be rotated inside a hole or outside a ring, and it will cut in 360 degrees.
Great for the inside of ring shanks and also for deep burring. A diamond needle file in a half-round shape, 220 grit, is also great for the inside of rings and bangles, and it has a nice, wide, flat profile, so that it can be used on the outside of rings without changing files. A great companion to the 600-round file.
2. Sharpening Carbide Cutting Tools
Over time, tungsten carbide cutting tools will dull, and it is often easier to have a hand tool abrasive that you can take straight to the cutting tool, rather than having to take a cutting tool to an electric grinding wheel. 600 grit diamond files are the best grade for this application on tungsten carbide.
3. Enlarging Holes
A round diamond needle file can be used for opening up a huge array of holes in hardened surfaces, 600 grit being the most common for most applications. Small screw holes in watches and clocks to holes in jewels and beads can all be opened up with a round diamond file. Choose diamond files that are either 600 or 900 grit for the best results.
4. Removing Excess Solder
If you solder a post onto the back of an earring, for example, a square 900 grit diamond file will help you get right into that solid joint and clean up both the horizontal and vertical surfaces. It also has a very nice sharp point. A round diamond file can be used for removing excessive solder inside a ring band and the finish is finer than what you would achieve with a traditional ring file.
5. Fitting Clock And Watch Glasses
Sometimes, the sizes need to be altered slightly when fitting watch or clock crystals. Using a 600-grit diamond needle file will produce the required result in minimal time.
6. Refacing Clock & Watch Pallets
Clock and watch pallets are very hard and become burred and misshapen over time. Using a 900 grit fine diamond file can radically change the surface of the pallet for a more efficient movement.
The above image shows Brad Taylor of taylorhorology.com using a 900-grit small square diamond file
7. Shaping Precious Stones For Jewellery
Precious stones can be extremely hard, especially quartz, sapphire and ruby, and small alterations may be required when setting stones into jewellery. No other abrasive will have such an effective impact as a diamond needle file. Fine grades such as 600 and 900 grit are ideal for making these small adjustments. Try a small flat 600 grit file, or a small half-round 900 grit file for superfine finishes.
Lucylou designs uses a diamond file to shape and smooth her cabochons, as seen above.
8. Repivoting Clock And Watches
Removing the burrs and wear from pivots is often tricky due to their hardness, especially in French clocks. The use of a 600-grit diamond needle file can have the pivot running smoothly in no time at all.
9. Bevelling Cut Crystal Glasses And Filing Glass
We all know it is easy to chip the rim of your precious crystal glass, and due to the cost of replacing one in a set, using a diamond needle file can be far more economical to bevel the lip of the glass. It is essential that a 600 grit diamond file is used, and a half-round shape is by far the most versatile for the contour of the glass.
The above image shows a glass bottle that has been cut, the edges of which are being filed down with a large square 600 grit diamond file.
Small 600 grit files are great for filing the edges of mosaic pieces as well
10. Sharpening Household Objects
Scissors, penknives, garden tools, kitchen knives, small screwdrivers, and guitar and violin strings can all be sharpened to a razor-sharp finish in very little time. You can use various sizes of diamond files for this application, but a 600-grit is recommended.
11. Cross-graining Burnishing Tools
Over time, burnishing tools lose their burnishing ability. Only diamond files can re-address the cross grain of a sapphire burnisher or hardened steel burnisher. Opt for the 600 grit for the best results.
12. Sharpening Fishing Hooks And Ice Screws For Winter Climbing
One of the most important tools of an angler has to be his hook, and in carp fishing in particular, this has to be razor sharp (sticky sharp). The use of a Flat 600 grit diamond needle file is ideal for this due to its size and profile. It is essential that the very hard-to-find diamond escapement file is used for this operation; this allows dexterous filing all around the hook point.
How to Clean Diamond Files
Always use your diamond files wet where possible, as this will help prevent debris from becoming lodged in the diamond grit. If you still find material clogging up your diamond file, you can try any number of the following:
- mild soap and a bristle brush (i.e. a toothbrush)
- brass or steel bristle wheels run in a rotary tool
- aluminium oxide or soapstone - rub the file across the surface
Recommended Diamond Files
We stock a wide range of diamond files ideal for jewellers, horologists, hobbyists and DIYers. Whether you're shaping gemstones, filing glass or repivoting clock pivots, you'll find the right file for the job.
Our 600 grit half-round diamond file is perfect for filing the edges of glass and working on the inside of ring bands. For ultra-fine finishing work in watch and clock repair, our 900 grit square diamond needle file offers superb control and precision. If you’re sharpening fishing hooks, household tools or knives, the flat 600 grit diamond file is an excellent choice due to its profile and cutting ability.
Browse our full collection of diamond files here to find the ideal tool for your next project.
Find Your Perfect Diamond File
Browse all our diamond files and burnishers here to find the perfect shape and grit for your task.
