If you are starting in granite business or you are in it already, here’s what experienced professionals check every time they buy this Jurassic natural stone.

About granite

The quality of granite generally differs significantly from place to place, sometimes even in the same place, with great variation in the pattern and composition of the slab.

Granite slabs are a common type of igneous rock or magmatic rock, which is a form of the slow crystallization of magma below the Earth’s surface. Granite slabs are essentially composed of minerals: quartz, mica and feldspar, with accessory minerals mica, zircon and other minerals (wikipedia).


The granite is extracted in blocks, but the slabs are delivered to our factory in the form of tiles or as requested. Granite slabs are used for floors, stairs, facades, countertops, tables, baseboards, parapets, fences, kitchen counters, etc.

how to verify granite quality at gra2003

Here 7 ways to check granite quality

  1. Confirm the hardness. When hitting the stone lightly with a hard object, the granite must withstand the hitting and sound thick.
  2. Check the thickness. The minimum thickness you can achieve starts at 10mm, but varies depending on the granite characteristics and the project’s needs.
  3. Check the color. It is possible to obtain granite in the color you are looking for, but as it is a natural stone, color and homogeneity varies, even in the same block. This variability is what makes each slab unique.
  4. Check the cut quality. The edges can have different shapes (rounded, beveled, straight, among others) check that they are as requested.
how to verify granite quality at gra2003

If you chose polished granite:

  1. Check the quality of the polish. A good polish has a mirrored surface. Check by scraping the surface with a coin and if it leaves scratches it means that the polishing must be of low quality.
  2. The upper layer must be uniform, straight, without cracks, holes and cavities.
  3. To check the porosity of the kitchen granite, place 3 or 4 drops of lemon juice (citric acid) on the granite surface. If kitchen granite slabs absorb lemon juice quickly, it means that granite has high porosity and is therefore not suitable for kitchen countertops.
how to verify granite quality at gra2003
how to verify granite quality at gra2003

These are just a few tests that you can apply to certify the quality of the granite. Stricter tests must be carried out in the laboratory to ensure that they comply with customer or legal requirements according to the application of the granite slab.

Adapted article. Originally published by Gharpedia.

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