TUNING: Diamond Stones
Written on March 25th, 2024 by Eliot Cochrane
Diamond Stones
A Beginner Tuner's Best Friend
“Diamonds are a girl’s best friend.”
Popularized by Marilyn Monroe in the early 1950s, the song became an icon in pop culture. Even though Monroe herself said that she was never into diamonds as much as the song portrayed, for those getting into edge tuning, diamonds might be the best thing to have in a ski tuning toolbox.
Photo: Author’s unorganized mess of a tuning toolbox.
Beginning to tune skis can seem daunting. Many YouTube tutorials mention files slipping off the edge and scratching the base or making a mess of the tuning area. Any tutorial then ends with diamond stones as the final step, so why not take out the risk but still produce a sharp edge?
Today we’ll take a deeper look into tuning edges so that even when there is no fresh Japow, we can still get out there and shred the slopes. Let’s get started.
Why Edges Matter
For those living the powder only ski life, edges might not have even mattered. The edges aren’t cutting anything, and the snow beneath the skis provides enough resistance to hold enough body weight to make a successful turn. But take away the powder, and what does that leave?
Photo: Author carving on freshly tuned skis.
This is where ski edges matter. Once the fluffy snow is taken out of the equation, the ski’s edge becomes the main contact with the snow or ice during a turn. To get into this snow or ice beneath the skier, the ski needs needs to cut into it. A dull edge isn’t going to want to cut into the hard-packed snow or ice. A nice sharp edge, similar to a knife, will cut in and give a good platform to make turns and feel in control.
Different Diamond Stones
Similar to sandpaper and files, diamond stones also come in different shapes and textures. Today we will be looking at the Swix Diamond Stone Set that can be bought anywhere. Most tuning companies like Holmenkol, Gallium, Sidecut Tuning, and Toko all have their variations.
Within each of these package products, there is a selection of diamond stones that can be broken down into three types: coarse, medium, and fine. Like sandpaper, these are broken down into categories using their grit. Grit is the measurement of the size of the abrasive particles. For diamond stones, these are rejected natural diamonds or natural diamond waste material that can still be used. The higher the number, the finer the finish.
Photo: Diamond stone set with aluminum backing from Swix.
Coarse - 100〜200 grit
This is typically the starting diamond stone that will be used in the process. It will remove the most material within the diamond stones that are available in the set. While it may take the most edge off within the set, it is SIGNIFICANTLY less than a traditional file. Paired with a file guide, this will set the edge.
Medium - 400〜600 grit
Here the polishing process begins within this range of stones. It will remove less material and get the valleys and mountains produced when using coarse diamond stones much closer in depth. Generally, it is cleaning up the set cuts from the coarse stone.
Fine - 800〜1000 grit
Finer stones are for the final polish and finish that gleams the best finish. It will remove very little material and will be hard to tell if it is removing any material at all. While it might not feel like it is cutting, it will be evident in the water used to lubricate the stones as they pass. This is the final step, and for most skiers, it may not be necessary to use this stone, but it is good to have anyway.
Tools For The Job
| Tool | Purpose |
|---|---|
| Tuning Vice | Creates a stable platform to hold the ski |
| Brake Retainers | This will hold your ski brakes up for tuning |
| File Guide | Provides a degree-accurate platform to make a measured edge |
| File Clamp | Fastens the stone to the guide to prevent movement |
| Gummy Stone | Used to remove rust before using diamond stones |
| Diamond Stone (Coarse) |
The starting stone that takes off the most edge material |
| Diamond Stone (Medium) |
A great all-rounder polisher and finisher |
| Diamond Stone (Fine) |
Provides the best polish and finish |
| Bowl of Water (mixed w/ soap) |
For cleaning the stones and lubrication during tuning |
| Old Toothbrush | Apply water on edge and scrub stones |
| Tissues/Paper Towels | Dry and remove edge particle-filled water from the edge |
Optional Item
Sidewall Cutter
This will cut into the ski material that supports the edge. If the sidewall is not cut away enough, it will not allow the diamond stones to make full contact with the edge and will not leave the edge at the desired degree when using the stones.
Let’s Get Tuning
Step 1 - Edge and Sidewall Check
Photo: Cross-section of ski showing names of individual parts of ski.
Here we are looking to make sure that the edge is in good condition, meaning that it has not separated from the ski itself and is not damaged in a way that will damage the tuning materials. If there is excessive damage, a file may be required, or if there is extreme damage, a full stone grind may be necessary.
Also, on the edge, we are looking for rust that will create pockets within the ski. These are discolored gray and dark marks on the edge of the ski. In extreme circumstances, the universal orange color of rust will be present. This will often happen when the edges are not dried after skiing. Before using diamond stones, remove all rust using a Gummy Stone.
The sidewall also needs to be checked. More than the condition of the sidewall, we are looking to check that the sidewall will not interfere with the diamond stone as it removes material. If the sidewall material interferes with the edge removal, the sidewall cutter tool can be used to bring it back behind the edge.
For the lazy folks like me (or those who don’t have confidence), at the beginning of the season, go for a stone grind to set up the skis for the season. If the shop accepts requests, ask them to cut off a little more sidewall than usual so that way throughout the season the sidewall will be maintenance free!
Step 2 - Using The Stones
Put the diamond stones in the bowl of water to soak. During that time, put the brake retainers on and put the ski in the vice. Take the toothbrush, dip it in the water, and use it to spread water along the edge. It doesn’t need to be perfect.
Once the edge is ready, take the file out of the water, put it in the file guide, and clamp it there, so it won’t move. See the picture as to how it should look.
Photo: Setup of the diamond stone, clamp, and edge guide from Ski Magazine.
From there, gently go back and forth, up and down the ski. Every 4 or 5 strokes, put more water on the edge using the toothbrush and also apply more to the diamond stone cutting surface.
If the edge is being removed, there are two obvious indicators:
- Water Darkens
- Edge Color Changes
Photo: How to use the diamond stones with the edge guide from Ski Magazine.
As the water mixes with the removed edge particles, it will darken in color. This means that the stones are cutting the material. With edge color changes, it should be progressive along the height of the edge. Once the formerly full edge color becomes a vibrant silver color, use tissues or paper towels to dry the edge and verify edge material has been removed along the entire edge.
Look For:
- Consistent color of the edge
- The edge maintains smoothness across multiple viewing angles
- Areas that may have been pitted from rust
- Gently check the edge to feel it is sharper than before
Step 3 - Stone Progression
Coarse > Medium > Fine (optional)
Along this process, be sure to keep the edge wet as much as possible and dry the edge with tissues or paper towels to verify that the edge material is being removed. Cleaning the stones is also encouraged so that the abrasive materials are clean to make a clean removal.
Typically, the coarse stones will require fewer strokes or passes as it takes away more material. But if there are severe rust pits or edge damage, it may require more strokes. Use plenty of lubricating water to make sure the stones keep cutting.
With each stone, the feel that the edge is being removed will be lessened. Each diamond stone is removing less and less material, so the lower the grit, the more it feels like it is pulling material. The higher the grit, the less it feels like it is doing anything. Be sure to check the water’s color during this process.
Step 4 - Dry & Check
Be sure to dry the edge with tissues or paper towels to reduce rusting that can happen between the tuning and the next ski day. When drying the edge, check for an even finish that does not have obvious cut lines along the edge.
Onwards, the skis are sharp they can be dangerous. Be aware not to overly grip the edge and also be aware when picking up skis or giving them to another person. The edges will cut into the skin if not handled carefully. Even when skiing, there have been major cuts during crashes or accidents. This is always a possibility that is added to an already risky sport. Always keep a sharp eye (pun intended) on edge sharpness to not harm yourself and those nearby.
Simple Takeaways
Fine Stones May Not Be Necessary
Fine stones are great for providing a great finish for a ski racer. But for more than 95% of the people skiing out there today, a mirror-like edge finish is probably not necessary. Save some time and just end at medium.
Taking Less Is More
We are using diamond stones because they are easy, but they also have another benefit. The life of the ski will be dramatically longer. Instead of removing a large amount of excess edge material using an edge removal machine or a traditional file, diamond stones remove the least amount of material and can allow the ski to be used for many more years to come.
Routine Maintenance
Instead of waiting until the ski edge is severely dull, using diamond stones periodically can help ensure readiness at any time to hit the hard-packed or icy slopes in the event that tuning can’t be done the night before. Even on blizzard days, with the right winds, there are always moments where icy spots will appear, and having a proper edge at any time can give the stability to not quiver on ice.
Photo: Traditional file and diamond stone side-by-side.
Being a beginner at tuning doesn’t mean you can’t have great skis that can perform in all conditions. Using diamond stones can help to become a better skier by providing the chance for the proper level of control that is needed, regardless of condition. It’s so easy and simple and with really low risk. The risk of damaging the ski and yourself is virtually zero and can be done easily.
Don’t let dull edges be a bane when the weather doesn’t go as hoped. Because diamond stones are truly a skier’s best friend.
