The prong is the most popular setting. A prong is a narrow piece of metal that folds over the edge of the gemstone to secure it. A prong setting appears to elevate a stone higher than in other settings, and is used most often with diamond solitaires.
Invisible setting is relatively new. Calibrated stones with slits are placed into a frame with ridges to hold them in place. No metal appears between any stones. This setting only employs baguettes and princess cuts or a combination of both.
Smaller stones are closely set in a row between two metal walls. No metal appears between the stones. Channel settings often include square and baguette stones. They are frequently used in engagement bands or as side accents to a center stone.
The word actually comes from the French word to pave because of its paved look. The round stones are patterned very closely together and the only metal visible is what is actually used to hold the stones in place.