The Diamond Dagger has evolved…
into the Diamond SharkFin

Diamond Dagger DNA. SharkFin control.

If you came here looking for the original Diamond Dagger, you’re not lost.

The Diamond Dagger earned a loyal following because it brought FretGuru’s D.I.A. crowning philosophy into a diamond format many luthiers prefer – smooth, controlled, accurate, fast-cutting, and built for tight fret crowns.

But rather than simply repeat the same design, we carried that diamond concept forward into our newest crowning platform.

Meet the FretGuru Diamond SharkFin

The Diamond SharkFin gives you the diamond crowning experience that demanding luthiers, repair techs, and passionate guitar geeks loved in the Diamond Dagger – now with the top-down control, relaxed grip, and natural hand position that make SharkFin feel so refreshingly different at the bench.

In head-to-head testing, the Diamond SharkFin delivered everything we loved about the Diamond Dagger – but with better comfort, control, speed, and cutting feel.

Same precision-first D.I.A. philosophy.

New SharkFin control.

And now with a durable, fast-cutting 300 grit industrial diamond surface that cuts smoothly in both directions.

The Diamond Dagger didn’t disappear.

It evolved.

Or, less formally:

It got swallowed by a Shark.

Diamond cutting feel. SharkFin control.

The SharkFin design puts your hand directly over the cutting action, giving you more direct control over the fret crown and centerline. Instead of death-gripping a long handle from behind the work, you can guide the file from above with a more relaxed, natural stroke.

With SharkFin, the shape of the handle plus the natural weight of your hand, combined with D.I.A. geometry and fast-cutting diamond grit, do most of the work for you.

Luthiers who’ve used the SharkFin have been thrilled with the fatigue-reducing benefits of the design. It’s counterintuitive just how little effort it takes compared to conventional crowning files:

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Very Comfortable!
5 out of 5 stars

This thing is amazing. My hands get fatigued very quickly. I was actually able to crown the entire neck in one sitting.

SD – Amazon Verified Purchase

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For those who’ve spent years, or even decades, crowning with traditional files, it can be helpful to do a quick mental reset when beginning to use SharkFin by asking:

How lightly can I grip?

How little pressure can I use?

The 300 grit industrial diamond surface cuts fast, clean, and smooth in both directions, making the Diamond SharkFin an excellent choice for stainless steel, nickel-silver, and precise high-control fretwork.

And with a diamond cutting surface, there’s no need for constant cleaning to stay ahead of fret debris getting stuck in the teeth.

Just durable and precise diamond cutting performance, with the most comfortable and controlled fret crowning format ever: SharkFin.

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Life changing for fretwork!
5 out of 5 stars

This thing is unbelievable, completely changed how I approach fretwork. Used to dread it, and felt like I was guessing – with this hand position I know where I am on the fret, and have way more control.

Also super easy to throw on various grits of sandpaper to get to a final polish. Game changer!

Chapman Swaine – Amazon Verified Purchase

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First batch is limited

This first production run is very limited, and people on the waitlist are getting the first heads-up (and the waitlist is much larger that the amount of files on hand).

If you were waiting for the Diamond Dagger, this is the evolution of that design philosophy:

Diamond Dagger DNA.

SharkFin control.

300 grit industrial diamond cutting power.

Features the same exact MD/LG/XL size and D.I.A. cutting geometry as the Diamond Dagger, which covers fret widths in the range of approximately 0.085" to 0.110".

If you’re working on vintage-style wire, 6105, medium jumbo, or most common modern fret sizes, this is the Diamond SharkFin to get.

The Diamond Dagger set the direction.

The Diamond SharkFin moves it forward.

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Excellent file - no pain and excellent results!
5 out of 5 stars

I’m part of the way through my first level and crown with the SharkFin file and I can already say this is a HUGE upgrade from the baroque file and the copy of the dagger file that I’ve been using.

It makes a much nicer crown with very little pressure, and the file shape makes it completely painless. I have psoriatic arthritis, so anytime I did a crown and level I was out for the count the rest of the day and often the next.

Pain from other files made my neck, shoulders, and hands feel like they were on fire, then locked up. This is going to make it so much easier and the result are going to be better.

I bought the diamond coated version, and I’m glad I did that, I’m sure that has a lot to do with the minimal pressure needed.

But the handle shape, putting your hands right over the file as you use it, is making a big difference too.

I could feel what I was doing much better, and I didn’t have to tilt the file as much at the edges, which will lower the chance of fretboard damage as well as being more consistent with the neck radius.

This is 100% recommended.