Typically, baguette diamonds are cut into a shape that looks similar to a French baguette, a long, narrow loaf. They come in all different sizes and shapes, but the ones that are slightly wider and longer are the most common. They were introduced to the world in the early 20th century as a new modern cut that was the most popular during the Art Deco era with its distinctive geometric shape that was typical for that period.
Because fewer cuts are required, baguette diamond rings are typically less expensive than other diamond cuts. They'll probably cost less per carat than, say, a round brilliant or an emerald cut. They are graded using the 4 C's, just like any other diamond, and their price will vary based on how they are graded.