How to Sharpen Ceramic Knives

Using an Electric Sharpener

Clean the ceramic knife. Before you do anything, it’s best to make sure the knife’s blade is clean. Run the blade under warm water and carefully scrub with a soapy sponge. Rinse and dry the knife. Try your best not to drop a ceramic knife. Unlike metal knives, ceramic blades are extremely brittle and can chip or break if handled too roughly.

Place the electric sharpener on a flat, sturdy surface and plug it in. Make sure the sharpener won’t wobble or tip while sharpening. Double check that the electric sharpener is for ceramic blades, as the sharpening mechanism is different from metal knife sharpening tools. There are ceramic knife sharpeners that run on batteries or are manual. These are similar to using an electric sharpener; just make sure they’re designed for ceramic knives.

Turn on the sharpener and press the knife’s blade into slot one. Electric sharpeners have numbered slots that indicate the order you sharpen your knife. Check the manual of your sharpener to see what each number specifically means. Generally, the numbers will range from 1 to 3, with 1 being the lowest and first level.

Pull the knife toward you slowly. Start at the base of the knife, gliding it through the slot till you get to the blade. You’ll be able to hear the electric sharpener working.

Slide the blade through the second and third slots, respectively. Follow the manual’s instructions in the order you need to sharpen the knife. Some electric sharpeners have 2 slots, while others have 3. Sticking to the sharpener’s order is crucial as the blades inside the sharpener are different for each numbered slot. Some electric sharpeners have a slot specifically for serrated knives, so be sure to use the appropriate slot for those knives.

Using a Diamond Stone

Place the diamond stone on a flat, slip-free surface. Lay a kitchen towel over a cutting board to create a great makeshift workstation. Just make sure everything is flat and that the stone won’t move around when you’re sharpening. You can also hold the stone in your hand, but that may be difficult if you're sharpening for the first time. If your diamond stone has two sides, place the stone coarse side up.

Hold the knife with the edge of the blade facing away from you. The blade should be flat against the stone with the sharp edge pointed towards the top of the stone.

Run the knife downwards in circular motions at a 16-degree angle. Imagine you’re trying to shave off the top layer of the stone. Use the same types of strokes you’d use when shaving with a straight razor. Keeping the knife’s blade between a 16- and 21-degree angle follows the natural curvature of the blade. Be gentle when applying pressure on the blade. Ceramic knives are extremely brittle, and too much pressure could cause the blade to snap or crack.

Flip the knife over and repeat. Turn the blade so the side you haven’t sharpened faces the stone (the sharp edge should be pointing towards you). Move the knife upwards in a circular motion along the stone, following the natural shape of the blade. Basically, you’re using the same motion as before just in reverse. Sharpen each side 6 times. Counting each drag of the blade can help you keep track.

Sharpen the knife on the other side of the diamond stone. Flip the stone over to the finer side. Run the blade over the stone using circular motions at a 16-degree angle. Remember to do the same number of drags on each side. The finer side will smooth and shine the blade.

Using a Diamond File

Set the knife in the diamond file’s holder. Some diamond files come with a knife holder that holds your knife at the perfect sharpening angle. Simply set the blunt end of the blade inside the holder (the edge of the knife will be tilted upwards). If your file doesn’t come with a holder, use your non-dominant hand to hold the blade at a 20-degree angle.

Wet the diamond file if you’d like. Adding water to diamond-based sharpeners isn’t necessary. Some knife wielders advise against it, while others swear the lubrication helps sharpen the knife.

Use up and down motions to rub the file from the hilt to the tip. Keep one hand at the base of the knife to hold it in place. Use gentle scrubbing motions to move the file from one end of the blade to the other. File for at least 1 minute. Ceramic knives are very brittle, so use gentle pressure when filing to avoid chipping or cracking your knife.

Flip the knife over and repeat. File the other side of the knife’s edge with similar up and down motions. There’s no need to add more water to the blade.