How to Miter Quartz Countertops

Installing quartz countertops can add beautiful, durable and easy-to-maintain surfaces to your kitchen or bathroom. However, creating clean 45-degree mitered joints where the countertop changes direction, such as at inside corners, requires some special techniques. With the right tools and preparation, you can achieve seamless mitered edges that highlight the elegance of quartz.

What You Need to Miter Quartz Countertops


  • Circular saw with diamond blade
  • Angle grinder with diamond blades
  • Sandpaper (120 to 220 grit)
  • Straightedge
  • Clamps
  • Safety gear (goggles, respirator mask, gloves)


  • Quartz slabs
  • Colored silicone caulk


  • Basic carpentry skills
  • Understanding of angles and geometry
  • Patience and attention to detail

Steps for Mitering Quartz Countertop Pieces

1. Measure and Mark the Miter Cuts

Carefully measure the inside corner where the two countertop pieces will meet. Transfer the 45-degree miter angle to each piece using a combination square, protractor or adjustable angle finder. Mark the cuts clearly with a pencil.

2. Make the Initial Cuts

Use a circular saw equipped with a diamond blade to make the miter cuts on each piece. Cut just outside the lines so you leave some extra material for the final trimming. Clamp a straightedge to the quartz as a guide if needed. Go slowly to avoid chipping.

3. Fine Tune the Miters

Use an angle grinder with a diamond blade to carefully trim and polish the miters. Test fit the pieces and hold them up to the light to check for gaps. Continue trimming a little at a time until you achieve a tight seam.

4. Secure the Pieces and Apply Silicone

Once the miters fit perfectly, clean the edges well. Apply colored silicone caulk to the seams and clamp the pieces together securely. Allow the silicone to fully cure for 24-48 hours before installing the countertop.

5. Finish and Install

Sand any unevenness on the finished miters with 120 to 220 grit sandpaper. Carefully clean and install the countertop. Apply a bead of colored silicone where the miters meet the walls for a seamless look. Allow to fully cure before use.

Tips for Achieving Perfect Mitered Edges

  • Use calipers to precisely match the miter angles.
  • Ensure your saw blade and grinder are high quality diamond for smooth cuts.
  • Go slowly and check miters frequently when trimming to avoid overcutting.
  • When test fitting, look for gaps by holding the joint up to light and use a bright flashlight.
  • Use painter’s tape along the seams to avoid damaging the polished edges.
  • Match the silicone caulk color to your quartz for almost invisible seams.

Common Mitering Mistakes to Avoid

  • Inaccurate angle cutting resulting in gaps.
  • Chipping, cracking or breaking the slab.
  • Misalignment because of not securing pieces.
  • Forgetting to account for the blade width when marking cuts.
  • Rushing through initial cuts or final trimming.
  • Using too much silicone and making a mess.
  • Not allowing adequate time for the silicone to fully cure.

Frequently Asked Questions

What blade should I use to cut quartz?

Use a diamond circular saw blade specifically designed for cutting stone and quartz. Diamond blades last longer than standard blades and provide smooth, chip-free cuts.

What type of saw is best?

For mitering quartz, a circular saw typically works better than a miter saw. Circular saws allow you to lay the slab flat to get perfectly straight cuts. Make sure to use a clamped straightedge guide.

Should I use water when cutting?

Water is not necessary when cutting quartz with a quality diamond blade. In fact, getting the slab wet can reduce the blade’s effectiveness. Keep the cutting area dry.

What grit sandpaper should be used on quartz?

Use 120-220 grit sandpaper to smooth and polish the cut edges of quartz. Higher grits aren’t necessary for quartz which has a non-porous surface. Be sure to sand evenly and avoid rounding over the corners.

How long does silicone caulk take to cure?

Silicone caulk typically fully cures in 24-48 hours. Avoid putting any strain on the miters during this time. Some silicone varieties may cure more quickly, so check the product directions.


Mitering quartz countertops involves careful measuring, precision cutting, test fitting and polishing to get perfectly matched seams. With the proper tools and techniques, you can achieve flawless mitered corners that accentuate the look of your quartz countertops. Taking the time to check angles and trim slowly results in tight joints that withstand the test of time.