Agate is a variety of quartz characterized by its fine grain and bright color, and it is traditionally associated with volcanic rocks. One of the most common materials used in hard stone carving, agates vary from shades of red, orange and yellow to rich burgundy and clay-colored hues. Though carvers seeking to cut fine details or intricate designs into agate will require specialized lapidary equipment (often available for rent at lapidary clubs) most general cuts can be made with a diamond-tipped bandsaw after tumbling.
Designate a workspace for tumbling and cutting your rough agate. Ensure that the area has ample light for working and is clear of any dirt, dust or debris.
Open the rock tumbling mechanism and insert the rough agate chunk along with the coarse grinding powder (available at most gem suppliers). Add water to the rock tumbler chamber until the particles are submerged, close the tumbling mechanism and begin the tumbling process. Let the tumbler run for one week.
Clean out the tumbler and replace the stone and water along with a fine grinding powder and restart the tumbling process for one more week.
Remove the tumbled agate and dry off the stone, removing any attached grinding powder or debris that may be attached to the surface. Decide on the types of cuts you wish to make on the rough agate, such as: halving the stone, carving it into slices or cutting shapes into the stone.
Put on your safety goggles and gloves and bring your tumbled agate to the band saw. Turn the saw on and carefully insert the stone by gently feeding the stone with two hands. If the stone section is too small to safely hold in place while the saw is in motion, secure the stone between locking pliers, such as Vise-Grip, and carefully direct the stone through the saw while holding the plier handles. Repeat for all desired cuts.
Polish each cut piece by placing each individual slice into the tumbler for several days, using water and polishing powder.
For occasions wherein you wish to cut multiple, even slices of a single agate section, completely tumble the rough agate for an additional week with polishing powder to decrease the amount of polishing required following the cuts.
Always practice caution when working with power tools such as the band saw. If flecks or debris fall off the agate during cutting and must be removed, turn off the saw before reaching to any area immediately near the blade. Never leave the saw plugged in unattended.