Once completely dry and solidified, polish the cement. Wearing safety gear working in a well-ventilated area, sand the surface of the cement in a circular motion. (Tip: An orbital sander will speed up the process.) As you sand, speckles of glass will appear, but avoid sanding too deep lest you expose too much glass. You can stop at this point like me if you are looking for the natural matte look. However, you may proceed to use a sealer of your choice for better durability and a polished finish.