Zenger Stone provides always do the business as italy design,america quality and chinese price. 
Our Quality Control Department is responsible for quality testing of all stone raw materials and finished products,

We will check with clients about the quality before order with slabs and block.

Before shipment, All products will be checked and inspected seriously by our professional and skilled Quality Controller (QC), according to strict quality control system during processing, packaging, label,Container loading.

Our QC is responsible for overall stone quality control systems, procedures, stone packing, they are very carefully to inspect each piece of tiles from your orders, select out the unqualified products, and supervise the cutting, packing and whole procedures in factory. We are taking good care all details for your order,, as always we will make sure all of your order in goods situation, we guarantee that when our customers received our goods, with great satisfy and happiness. 

Polishing:
Polishing will be uniform throughout the slabs/tiles and in glossometer as: 
For black slabs / tiles : polishing +95 in glossometer 
For colored slabs/ tiles : polishing +85 in glossometer 
There should be no grinding wheel marks on the polished face.
Flaming: 
Flaming will be uniform throughout the slabs/tiles and brushed evenly on slabs after flaming 
Thickness: 
+/-1.0mm in tolerance for slabs;         +/-0.5mm  in tolerance for tiles 
Diagonal Out:
+/- 0.5mm in tolerance for tiles 
Flatness:
If length <= 400mm,flatness tolerance: +/-0.2mm 
If 400mm < length < 1000, flatness tolerance: +/- 0.5mm 
If length >= 1000mm, tolerance: +/- 0.8mm 
Length And Width:
+/- 0.5mm in tolerance for tiles and slabs (not apply to the random edge slabs).
Front Edge Defect:
Not allowed for slabs and tiles.
Front Corner Defect:
Not allowed for slabs and tiles.
Unpolished Side:
The unpolished side of the slab/tiles should be flat and smooth.
Crack: 
Not allowed for slabs and tiles.
Crack Looks Treatment: 
If slab/tile have crack looks (not the real crack, like paper been foddered but not tear down), please treat it.
Surface Treatment:
If it is possible, treat the slab/tile surface after it has been polished. So there is no little dent. This treatment is not required, but is recommended.
Billed Area Defenation:
For slab size > 1.2m x 2.2m, there should be a 1" (2.54 CM) allowance on each side of the slab to be taken out for the actually billed area.