When having dinner on a glass table it is very easy to scratch the top. Using a plate mat will avoid a direct contact with the glass. Although its very tough crystal structure due to the use of tempered glass within household it is way easier to be scratched by forks, plates and any dinnerware.
Do not forget to use a plate mat each time and this will keep it scratch free for longer.
Even if any small scratches appear, try speaking to a local DIY shop and they will advise you on the best product to be used to repolish the glass top.
Please note that use of metal or other scrubbers as well as sharp objects to remove spots or food from the table may scratched if tempered glass.