Machine flat polished edge
A flat polished edge is most commonly found on glass tops (thickness ranging anywhere from 1/4″ to 3/4″). The glass is run through a glass edging polishing machine with a number of polishing wheels, ranging in grits getting finer towards the end.
After the flat polish is created on the edge, the glass approaches two wheels angled at 45-degrees, which create the top and bottom arris, making sure the edge is no longer sharp.
A beveled edge is found on both glass tops, and mirrors hanging on walls with or without frames. Normally when found on a glass top, there is not full support underneath the glass, so the bevel can be seen. Examples being glass pedestals, or coffee tables with the center open.
The glass is sent through a beveling machine with a number of wheels again ranging in grit, getting finer towards the end. And lastly the glass encounters felt wheels along with cerium oxide to polish the bevel back to clear.
Seamed or broken edge
A seamed or “broken” edge is most normally used when the glass is going into a frame, and the edges are going to be covered. Glass edging can be expensive as usually it’s billed out per linear inch. Therefore if the glass is going to be inserted into some type of frame, there’s no reason to pay for the high end polish.
A seamed edge is accomplished by running an aluminum oxide based sanding disc ranging from 80 to 120 grit across the upper and lower edge of the glass.