Stone countertops are available in a wide range of different thicknesses. Some stones are more likely to be available in one thickness versus another, while others may be able to be built up to appear thicker than they are. Most counters, however, are available in standard thicknesses from the majority of fabricators.
2cm is one of the more common thicknesses for marble and some granites. Also known as ¾-inch stone, this is often a less expensive option usually seen in bathrooms. 2cm thick stone may be more prone to problems with overhangs if used in kitchens or on bars, and sometimes needs and underlayment of plywood for support.
3cm stone is the other more common thickness for most granites and some marbles. Also known as 1-1/4-inch stone, this is the preferred choice of most homeowners for kitchens and other larger counters. If the stone is durable enough, it can sometimes be used without any supports beneath it on the cabinets.
Some proprietary stones for sink legs and other decorative settings may be available in 2 or 3-inch thicknesses as well. This is particularly popular for Bianco Carrara and other white marbles, although it should be noted that most faucet stems are not long enough to go through this size of stone, so an extender is needed, or the stone should be carved away in the back to accommodate it.
Another popular option for homeowners that want the look of thicker stone, but not the accompanying expense, is to use a built edge. This involves epoxying another piece of stone to the underside of the overhang or edge and grinding and polishing the two pieces together into one edge. Unless you look closely at the edge to see the seam, it can make the stone appear to be much more substantial.
Some manufactured stones, such as agate and other gemstone-based counters, can also be produced or cast to have a thick-looking edge as well.
Countertop thicknesses are fairly universal, meaning that most fabricators will offer similar options to give you the most choices for your home.