This site on E-How basically explains the process in making a mosaic. Ensure that the thickness of the ceramic tiles used by breaking up with a hammer are all the same if you desire a flat surface.Ceramic tiles are less expensive than glass tiles, although both types of tiles have sharp edges when broken. The glass tiles give a bit more luster, so choice of tile material is a matter of personal preference. The small blue tiles shown in the above picture were made of glass, so the contrast was preferable not only in color, but also in textural effect.
The larger table top (44 " round) is almost finished. It still needs to have excess grout removed from the tiles. A picture of the larger table top (using same motif as smaller table) is shown below.
A Dremel tool to sand the edges will finish off the sides more smoothly.
While doing a bit of research on mosaics, I found this type craft goes back several thousands of years. One reference, found here says:
Some mosaics from the Byzantine era look very similar to how they appeared over 4,000 years ago. So my table tops should hold up well outside under the patio roof, at least during our lifetime.The history of mosaic goes back some 4,000 years or more, with the use of terracotta cones pushed point-first into a background to give decoration. By the eighth century BC, there were pebble pavements, using different coloured stones to create patterns, although these tended to be unstructured decoration. It was the Greeks, in the four centuries BC, who raised the pebble technique to an art form, with precise geometric patterns and detailed scenes of people and animals.
The mosaic here shows the god Neptune with Amphitrite (on the right) and is in Herculaneum, Italy. It is a wall mosaic which uses pieces of glass to give the vivid colours and reflect light. Glass was not suitable for floor mosaics.
