Ski Tuning 101 Presents: Diamond Stone Review

Diamond Stones, a buyer’s guide.

Terminology to know before reading: grit. The grit of a diamond stone is a measure of how aggressive the stones surface is. Think sandpaper. Grit numbers of 100 are very aggressive, whereas grits of 800 and up are much smoother. A 100 grit stone will remove dings and rust from an edge, and an 800 grit stone will smooth and polish an edge. Using multiple stones of increasing grit in succession will sharpen and polish an edge, and give the best results. To save money, a lot of skiers only buy a 400 “general purpose” grit diamond stone.

For this post, I’ll be taking a look at 4 popular diamond stones. They range in price from $16 to $27. It’s obviously hard to quantify something like the performance of a diamond stone, but I’ll do my best to illustrate the differences between the options at hand.

Before we get into the review, it’s important to quickly touch on technique. Specifically, the use of a polishing solution when tuning. I’ve written about this in the photo guide, but basically, a polishing solution is a lubricant that facilitates edge sharpening. It might come off as a gimmick, but it’s an incredibly important part of the process. ARTECH offers the most economical polishing solution: 2 oz’s for $7, or 8 oz’s for $18. The 2 oz bottle will easily get you through a season, as very little is needed.

The alternative to buying a polishing solution is to make your own. I’ve had success with liquid hand soap and water, combined in a spray bottle, and applied generously to stones before sharpening.

Lubricating diamond stones will yield superior results, and will also lengthen the life of a diamond stone by preventing it from clogging up with debris. Don’t skip this step!

1. The first stone shown here is the Swix Race Diamond File, which goes for a reasonable $16.

It comes in 100, 400, and 800 grits. It’s a great stone, and I definitely recommend it. Buying a 100 and 400 grit stone will make a great general purpose kit. Use the 100 for major dings and edge damage, and finish with the 400 to smooth things out. Adding an 800 grit stone will give an even smoother, harder, and sharper edge.

Here is a closeup view of the stone:

2. Next is the DMT Diamond Whetstone, which sells for $17, or $70 for a kit of all 5 grits.


I’ve used these stones quite a bit, but there is something about them that I just don’t like. I can’t put my finger on it, but I’ve just never been able to get the same results with the DMT stones as I have with the Swix or MoonFlex stones. The DMT’s come in grits of 120, 220, 325, 600 and 1200.

3. Up next is the Diaface MoonFlex Diamond File, retailing for $27.


I’ve also used these stones extensively, and they are far and away my favorite. The stones are advertised as being able to “cut and polish at the same time” due to the “crescent moon” design pattern. Now, I can’t speak to the science behind the patterns of diamond files. For all I know it could be a marketing gimmick, but first hand experience has led me to believe that there is something special about MoonFlex stones.

4. Lastly we have the Swix W.C. Diamond File Pro, for $29 a pop.

They come in grits of 100, 200, 400, 600 and 1000, and are noteworthy because they are the only stone with a metal handle reviewed here. The others all have hard plastic handles. I don’t know that this makes a difference in terms of performance, but other than that there is not much difference between these and the MoonFlex stones. Compared to the $16 Swix option, these are definitely worth the extra $13 for the serious tuner or racer.

Overall, the Moon Flex are my favorite diamond stones to use. The $16 Swix stones come in 2nd place for value and performance, and are what I would recommend to the average ski tuner.