Dry-fit the tile over the flange to make sure it fits. Check your work before you attempt to secure the tile in place permanently. So long as your circular cutout is less than 0.5 in (1.3 cm) larger than the toilet flange all the way around, the base of the toilet should cover the cutout. Once you know the tile fits properly, you can secure it to the floor permanently.
Reach across the tile to the edge that’s farthest away from you and set the wheel of the scoring tool on the end of the guideline. If the glass tile is too large for you to reach over to the edge, stand alongside it instead while placing your scoring wheel.
Pull the scoring wheel toward you using the straightedge as a guide. Press firmly down on the glass with the scoring tool as you pull it towards you. It should make a distinctive crackling sound as the tool scratches the surface of the glass tile if you are applying enough pressure. Look to see a faint but definite line cut into the glass.
Grip the section of glass you want to cut with grozing or running pliers. Grozing and running pliers have a flat, serrated jaws that are perfect for gripping and breaking scored glass. Keep the tile face up on the workstation or table and grip the edge of the glass with the pliers positioned parallel to the cut you made with the scoring tool. If your pliers do not have a rubberized grip on the jaws, apply masking tape to get a better grip on the glass.
Snap downward to break off the tile. Position the scored glass tile so the edge of the tile that you want to snap off is hanging over the edge of the table or workbench. This will give you room to snap the piece off. In one swift motion, snap the glass downwards using the pliers to grip it. The glass should break cleanly along the line you scored. Don’t press down slowly or the edge of the glass may break off unevenly.