When it comes to buying an agate stone, there are two different types you can get on the market: banded agate, and brecciated agate. Either is a good purchase if you are looking to steer away from the classical choices, such as a 1.4 carat round diamond ring, for instance.
The more typical type of agate, this stone has distinctive banding or light lines running all thorough the interior. This may at times be tight enough to cause a rainbow effect, but that is never enough to raise the stone’s value. The bands all have the same thickness, and some may be so small you cannot spot them outside magnification, much the same as the inclusions in a VVS diamond.
This type of agate contains rock chunks. In fact, “Brecciated” simply means broken, and brecciated agate is formed when many agate pieces mash together into a single rock, such as during an earthquake. Over time, amethyst forms around it, giving it the appearance of chunks of different stones, which is also called “ruin agate”, for its resemblance to ruined buildings. In brecciated agate, the original agate tends to contrast with the surrounding material when it comes to color.