I have sharpened my knives on whetstones for around 20 years.

(30+ minutes per knife)
In the beginning, I sharpened on inexpensive aluminum oxide stones that needed to be soaked in water. I did not achieve the results I was hoping for, and my skills did not improve, even though I put a lot of effort into it.

Later, I realized that sharpening well on soft aluminum oxide stones requires a great deal of experience.
Partly because the stones are soft and remove less material from the knife. This means you need to maintain a perfectly stable angle by hand in order to sharpen at all on cheaper stones.
A classic bootstrapping paradox.

(15 minutes or less per knife)
In my late twenties, I invested in Japanese splash and go whetstones, and that changed everything for me.
Naniwa and Shapton are good examples of manufacturers producing excellent Japanese splash and go stones.

Over the past years, I have tested and examined hundreds of sharpening stones to find something I genuinely want to use myself and sell.

(5 minutes or less per knife)
In 2024, I began testing coated and bonded diamond stones, and once again the game changed.

Because diamond is harder than steel, it can sharpen any type of steel and it does so quickly.
From carbon steel without chromium carbides to HAP40 with a high vanadium carbide content, diamond can handle it all.

And good luck sharpening most super steels like ZDP189, HAP40, and similar steels on ceramic whetstones.
It is going to take a very long time.

Beginners:

Use the free angle guide to learn how to maintain a consistent angle by hand.

1. #250 coated diamond

Shape the edge. Hold a stable angle. Use light to moderate pressure. Work until a small burr forms along the entire edge.

2. #1150 coated diamond

Refine the scratch pattern and reduce the burr. Use lighter pressure and flip the knife frequently.

3. Leather strop

Use only strokes away from the edge. Plain leather or a very small amount of diamond paste is sufficient.

Professionals:

1. #250 coated diamond (edge profiling)

2. #1000 bonded diamond stone (splash-and-go whetstone)

3. #3000 bonded diamond stone (splash-and-go whetstone)

4. #6000 bonded diamond stone (splash-and-go whetstone)

5. #12000 bonded diamond stone (splash-and-go whetstone)

6. Leather strop with 1.5W diamond paste (1 micron)