What 3 cm means on a countertop
Three centimeters is 1.18 inches, and the trade rounds it to 1 1/4. That is enough stone to rest directly on standard base cabinets in most kitchens, and enough depth to cut an edge profile straight into the slab. A 2 cm top usually needs both of those added: a plywood subtop to bring it to height and a laminated or mitered strip to thicken the edge.
That is why 3 cm is the default for kitchen counters and islands in most of the country, and why it makes up the larger half of the slab catalog. The thinner option and where it fits best are covered in 2 cm slabs.
Marble, quartzite and granite in 3 cm
Marble is the largest material in 3 cm, led by the Calacatta family in its many variants, from Vagli to Viola. Quartzite is close behind it, and this is where most of the quartzite lives: Taj Mahal, the blue Vitoria and Fusion stones, and the Cristallo group. Granite is the third group, from Absolute Black to Patagonia and Azul Bahia.
A few stones come only in 3 cm here. Soapstone is one, a dense, soft-feeling stone that darkens with use, and Absolute Black granite is another. Limestone, travertine and basalt make up the rest.
Hardness of quartzite, granite and marble slabs
True quartzite sits around 7 on the Mohs hardness scale and granite around 6 to 7, harder than most steel blades. Marble sits around 3 and soapstone lower still. That is why quartzite and granite are the usual picks for a working kitchen and why so much of both is stocked at the kitchen thickness. Marble is used on walls and vanities as much as on counters, and it is spread more evenly across the two thicknesses.
3 cm slab colors
White is the largest color group in 3 cm, mostly marble, followed by gray and then black, where granite and soapstone take over. Green and blue are unusually well represented, mostly through the quartzites and the exotic stones sold alongside them, such as the Vitoria blues, Fusion and the Cristallo group. Some stones traded as quartzite are partly dolomitic and behave closer to marble, and the fabricator can tell which a given slab is.
Beige and brown make up the warmer end, from travertine and limestone to the gold-veined quartzites. A single slab rarely stays one color across its whole face, so the color group is a starting point and the photograph of the actual slab lot shows the real color.
3 cm slabs on kitchen islands
An island is where the thickness shows most, because it is seen from all four sides and often has a seating overhang. A waterfall island takes the slab down the sides to the floor, with the top and the side pieces mitered so the vein turns the corner. At 3 cm that miter produces a solid-looking 1 1/4 inch edge on every face.
Islands are also where the largest pieces are cut, so the length of the individual slab matters more here than anywhere else in a kitchen. An island longer than one slab needs a seam, and the fabricator places it at the layout stage, ideally where the vein allows a clean match.
Weight of a 3 cm slab
Natural stone weighs roughly 2.7 grams per cubic centimeter, which works out to about 16 to 18 pounds per square foot at 3 cm. A full slab of 50 to 60 square feet is therefore close to half a ton. That weight is part of why slabs move on A-frames and why fabrication happens in a shop, not in the kitchen.
Edge profiles on a 3 cm top
The extra depth is what makes the classic edges possible without adding material. An eased or square edge shows the full 1 1/4 inches as one clean face. A bullnose, half bullnose or ogee is routed from the solid stone, so the vein wraps around the edge unbroken, which a laminated edge cannot quite match.
A thicker look than 3 cm is still possible, through a mitered apron that folds the stone down at the front. That is a fabrication choice made with the shop.
3 cm finishes
Polished is the most common 3 cm finish by far, followed by honed, then leathered and textured faces. Leathered and textured surfaces show up mostly on granite and quartzite, where they soften the shine and hide fingerprints on a dark island. The finishes are compared side by side in polished slabs and honed slabs.
When 2 cm may be the better fit
A 3 cm slab is more stone than a wall panel, a shower surround or a vanity top usually needs, and on a wall the extra weight has to be carried by the fixings. For those surfaces the 2 cm side of the catalog is the more common choice, and it also holds the onyx that 3 cm does not. How slabs are selected and quoted is explained on the stone slabs page.
