A gemstone such as topaz will scratch just about anything including quartz countertops but you can t use a wedge made of calcite to this effect.
Can you use a knife on granite countertops.
However if you cut acidic foods like citrus fruits the acid can degrade the surface of the countertop leaving a noticeable dull spot.
The granite is tough and can handle the knives.
Hard stone countertops like granite and quartz can withstand knife work in the kitchen without scratching.
Quite a few stainless steel knives rank around 7 on the mohs scale thereby enabling them to scratch quartz countertops which also rank around 7.
Use a cutting board if you may.
The answer is it depends and it s still better to use a cutting board.
Since knives are not typically made of granite or any other mineral you could purchase a granite countertop color and feasibly not purchase another cutting board as long as you have your kitchen.
However you can only do this up to a certain extent.
Just because you can doesn t mean you should.
Really you wouldn t have to worry about cutting on your granite countertop unless you were using a knife made out of granite.
Slicing knives across granite to cut food will quickly dull and damage their blades.
So to answer the question.
Yes you can directly cut food on quartz countertops since they can resist any scratching or slicing damage that is inflicted on their surface.
Don t use knives directly on the granite.
A quick chop here and there will not necessarily wear out your granite countertops.