• Sweep or vacuum your floors regularly
• Wash with clear water occasionally - if you use a soap make sure it is PH balanced
• Never use vinegar on natural stone
• Never use any cleaners that contain ACID - when in doubt don't
• Protect stone from sand and grit - use door mats
• Use a rag (string) mop verses a sponge mop - dirt gets pushed into the grout joints with a sponge mop
• Tend to spills quickly - sealer gives you a couple of seconds to clean it up.  Sealers DO NOT prevent 100% of damage due to spills
• Never apply wax or acrylics - this will damage the stone
• Use coasters, tablecloths or placemats
• Be careful with acidic drinks (lemonade, orange juice, etc.) they will etch natural stone.

PEI Classifications
The Porcelian Enamel Institute (PEI), started establishing wear resistance ratings for tile.  Although there are no real industry standards for tile, this abrasion test is recommended by the American Society Testing Materials (ASTM) and has become a common way to classify wear.  Below are the classifications for PEI.

Class 1 - No Foot Traffic
Ceramic tile suggested for interior residential and commercial wall applications only

Class 2 - Light Traffic
Ceramic tile suggested for interior residential and commericial wall applications for residential bathroom floor applications only

Class 3 - Light to Heavy Traffic
Ceramic tile suggested for residential floor, contertop & wall applications

Class 4 - Moderate to Heavy Traffic
Ceramic tile suggested for residential, medium commercial and light institutional floor and wall applications

Class 5 - Heavy to Extra Heavy Traffic
Ceramic tile suggested for residential, commercial and institutional floor & wall.