The answer is not simple, since it isn’t something that can be seen with the naked eye or something that is described in the data sheet, although there are some clues that can help you: 

• It is important to find out who is the real manufacturer, since there are many companies that present themselves as manufacturers when they are actually importing turf from Asian countries with lower qualities and offering it with guarantees as if it were manufactured in Europe. It’s much more difficult for you to have problems if the actual manufacturer of the product is European. The ESTC is a European association that groups the artificial turf industry, here you can see all the members (https://www.estc.info/members/) 
• Look at the warranty the manufacturer offers, the usual for our country is between 5 and 9 years. Keep in mind that warranty doesn’t equal lifespan. 
• Look at the thickness of the thread in microns. If you want to know more about it, you can read the following article.  

• The price. Very low prices are usually related with very low quality.