I've used triangular stones for pruning shears and secateurs, it works but is a little painful. However, this stone with the circular pattern recommended on the packaging works great and is much simpler.
USA Made Diamond Lapping Paste Polishing Compound 600 Grit Mesh 22-36 Microns For Rock Glass Metal Jewelry Resin Marble With High Concentration Of Diamond Powder By TechDiamondTools
30 Review
Sharpening stone Hatamoto HT0960, green
22 Review
Lansky 2D2C Diamond Ceramic Four: Ultimate Sharpening Solution for Precision
13 Review
π Enhanced Superfine Assortment: Various Sizes, Multi-purpose, and Reusable
10 Review