Which of the following is correct:
Supplier of tile, stone, tools and equipment
Supplier of tiles, stones, tools and equipment
If you could provide an English rule to know that would also be very much appreciated.
I think this is more of a contextual usage in the sense that if you use the word tile, you imply that one is supplying tile in bulk with (potentially) less variety. However, if you use tiles, you imply that the selection of tiles being supplied is more varied and that they are not supplied in mass quantities, but rather, smaller, more personalized amounts.
Needless to say, the same principle applies to the word stone and stones.
The local hardware shop was a "supplier of tiles, stones, tools and equipment."
Home Depot is a "supplier of tile, stone, tools and equipment."
Nevertheless, no one will criticize you for using tiles in the context of the latter sentence, and vice versa. It is more of a matter of opinion, and arguably the singular usage implies mass, general quantities, whereas the plural form implies variety and a smaller quantity supplied.
Hope this helps!