How to avoid buying a bad granite worktop for your kitchen

Granite isn't all the same. It's priced by quality and most people don't know what serious problems can occur if you use poor quality granite for your kitchen surface.

For instance, poor quality granite may be easily scratched and more heavily pitted. It can even twist over time or break in installation or after.

Cheaper granites are more widely available now in the UK from India and China. The best granites come from South Africa, Belgium and New Zealand. Think of your granite like a diamond: the price reflects the quality you're getting and the pleasure you'll get over the years.

Granite slabs can contain multiple hairline cracks, weak flaws along which the slab can easily break. Cheaper granites tend to contain more hairline cracks. The risk is that, particularly with slabs cut with holes for sinks (leaving two relatively thin 'arms' of granite around the hole), if the slab is twisted at all during installation, it is very easy to break. Be sure to agree who pays for a replacement. Slabs can shear after fitting too if there's any movement, and replacing a slab after all the fittings and tiles are installed is a problem job.

Low quality granite often isn't even the same thickness for its whole length, we've seen a slab lose 6mm in thickness from one end to the other. Even if it's not immediately obvious, take a look along the edge. If the thickness isn't consistent, that will need to be bolstered during fitting, costing you time and headaches.

A proper polished edge takes about an hour's labour per foot length and lasts practically forever. Cheaper granites aren't properly polished, but are given their shine using a spray on wax. Of course this wears off pretty quickly. You can scratch wax off with the edge of a coin.

Companies often claim fitters are employees, but they are most often contractors. The job is split between one person who measures the job, another who cuts the granite, and a final team who fit it. There's little communication between those teams, so, for instance, you can get problems with getting slabs through the door into the house. When something does go wrong, who do you blame? It's much better to use a specialist who measures, cuts and fits and who takes responsibility for the whole job.

The hardness of granite varies, and with software granites it's quite easy to mark them with an ordinary kitchen knife. Once marked, you can always tell, even if you have it polished out (you'll still see the dip). Ask for a sample and try to mark it.

Granite contains holes throughout, no matter how much you polish it. The question is: how many holes and how big are they. Look closely at the reflection of light in your granite to see the pitting. The fewer pits there are, the better (and the easier it will be to clean if you ever roll flour on it). Quality granite has fewer, smaller holes.

With a reputable supplier you can choose your own granite slab. Check it's a consistent colour from one end to the other, otherwise when you join two pieces, they won't quite match.

It's quick and simple to butt two granite surfaces together and stick them with sealant, but everything moves over time and how is that joint going to look over the months and years to come?

A good quality joint is pinned underneath to ensure that the joints remain tight over the life of your worksurface.

Granite should dry out properly before fitting. When it's cut it's drenched in water to cool the sawblades.

I don't recommend you do this, but if you apply a blowtorch to cheap granite you'll often see condensation from the water it contains.

Granite gets sealed. If water is sealed inside, the slab can bend and twist, just like wood, making for joints that aren't tight, or even worse, the stresses can make a worksurface shear along a weakness.

Your granite needs to be completely dry before installation.

Check your suppliers customer service record. Get references, check online for complaints, ask about guarantees and their procedures in case of complaint.

Many companies have appeared selling cheap granite with a brazen disregard for customer service. Ask how long your supplier has been in business.